diff --git a/backend.native/tests/build.gradle b/backend.native/tests/build.gradle
index bd2c277e2d1..bfa255c6c32 100644
--- a/backend.native/tests/build.gradle
+++ b/backend.native/tests/build.gradle
@@ -1884,6 +1884,11 @@ task array4(type: KonanLocalTest) {
     source = "runtime/collections/array4.kt"
 }
 
+task array5(type: KonanLocalTest) {
+    disabled = (project.testTarget == 'wasm32') // Uses exceptions.
+    source = "runtime/collections/array5.kt"
+}
+
 task typed_array0(type: KonanLocalTest) {
     goldValue = "OK\n"
     source = "runtime/collections/typed_array0.kt"
@@ -3860,6 +3865,12 @@ interopTest("interop_array_pointers") {
     source = "interop/basics/arrayPointers.kt"
 }
 
+standaloneTest("interop_pinning") {
+    disabled = (project.testTarget == 'wasm32') // Uses exceptions.
+    source = "interop/basics/pinning.kt"
+    flags = [ "-tr" ]
+}
+
 task interop_convert(type: KonanLocalTest) {
     source = "codegen/intrinsics/interop_convert.kt"
 }
diff --git a/backend.native/tests/interop/basics/pinning.kt b/backend.native/tests/interop/basics/pinning.kt
new file mode 100644
index 00000000000..0bc48331552
--- /dev/null
+++ b/backend.native/tests/interop/basics/pinning.kt
@@ -0,0 +1,247 @@
+/*
+ * Copyright 2010-2020 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license
+ * that can be found in the LICENSE file.
+ */
+
+import kotlin.test.*
+import kotlinx.cinterop.*
+
+@Test fun pinnedByteArrayAddressOf() {
+    val arr = ByteArray(10) { 0 }
+    arr.usePinned {
+        assertEquals(0, it.addressOf(0).pointed.value)
+        assertEquals(0, it.addressOf(9).pointed.value)
+        assertFailsWith<ArrayIndexOutOfBoundsException> {
+            it.addressOf(10)
+        }
+        assertFailsWith<ArrayIndexOutOfBoundsException> {
+            it.addressOf(-1)
+        }
+        assertFailsWith<ArrayIndexOutOfBoundsException> {
+            it.addressOf(Int.MAX_VALUE)
+        }
+        assertFailsWith<ArrayIndexOutOfBoundsException> {
+            it.addressOf(Int.MIN_VALUE)
+        }
+    }
+}
+
+@Test fun pinnedStringAddressOf() {
+    val str = "0000000000"
+    str.usePinned {
+        it.addressOf(0)
+        it.addressOf(9)
+        assertFailsWith<ArrayIndexOutOfBoundsException> {
+            it.addressOf(10)
+        }
+        assertFailsWith<ArrayIndexOutOfBoundsException> {
+            it.addressOf(-1)
+        }
+        assertFailsWith<ArrayIndexOutOfBoundsException> {
+            it.addressOf(Int.MAX_VALUE)
+        }
+        assertFailsWith<ArrayIndexOutOfBoundsException> {
+            it.addressOf(Int.MIN_VALUE)
+        }
+    }
+}
+
+@Test fun pinnedCharArrayAddressOf() {
+    val arr = CharArray(10) { '0' }
+    arr.usePinned {
+        it.addressOf(0)
+        it.addressOf(9)
+        assertFailsWith<ArrayIndexOutOfBoundsException> {
+            it.addressOf(10)
+        }
+        assertFailsWith<ArrayIndexOutOfBoundsException> {
+            it.addressOf(-1)
+        }
+        assertFailsWith<ArrayIndexOutOfBoundsException> {
+            it.addressOf(Int.MAX_VALUE)
+        }
+        assertFailsWith<ArrayIndexOutOfBoundsException> {
+            it.addressOf(Int.MIN_VALUE)
+        }
+    }
+}
+
+@Test fun pinnedShortArrayAddressOf() {
+    val arr = ShortArray(10) { 0 }
+    arr.usePinned {
+        assertEquals(0, it.addressOf(0).pointed.value)
+        assertEquals(0, it.addressOf(9).pointed.value)
+        assertFailsWith<ArrayIndexOutOfBoundsException> {
+            it.addressOf(10)
+        }
+        assertFailsWith<ArrayIndexOutOfBoundsException> {
+            it.addressOf(-1)
+        }
+        assertFailsWith<ArrayIndexOutOfBoundsException> {
+            it.addressOf(Int.MAX_VALUE)
+        }
+        assertFailsWith<ArrayIndexOutOfBoundsException> {
+            it.addressOf(Int.MIN_VALUE)
+        }
+    }
+}
+
+@Test fun pinnedIntArrayAddressOf() {
+    val arr = IntArray(10) { 0 }
+    arr.usePinned {
+        assertEquals(0, it.addressOf(0).pointed.value)
+        assertEquals(0, it.addressOf(9).pointed.value)
+        assertFailsWith<ArrayIndexOutOfBoundsException> {
+            it.addressOf(10)
+        }
+        assertFailsWith<ArrayIndexOutOfBoundsException> {
+            it.addressOf(-1)
+        }
+        assertFailsWith<ArrayIndexOutOfBoundsException> {
+            it.addressOf(Int.MAX_VALUE)
+        }
+        assertFailsWith<ArrayIndexOutOfBoundsException> {
+            it.addressOf(Int.MIN_VALUE)
+        }
+    }
+}
+
+@Test fun pinnedLongArrayAddressOf() {
+    val arr = LongArray(10) { 0 }
+    arr.usePinned {
+        assertEquals(0, it.addressOf(0).pointed.value)
+        assertEquals(0, it.addressOf(9).pointed.value)
+        assertFailsWith<ArrayIndexOutOfBoundsException> {
+            it.addressOf(10)
+        }
+        assertFailsWith<ArrayIndexOutOfBoundsException> {
+            it.addressOf(-1)
+        }
+        assertFailsWith<ArrayIndexOutOfBoundsException> {
+            it.addressOf(Int.MAX_VALUE)
+        }
+        assertFailsWith<ArrayIndexOutOfBoundsException> {
+            it.addressOf(Int.MIN_VALUE)
+        }
+    }
+}
+
+@Test fun pinnedUByteArrayAddressOf() {
+    val arr = UByteArray(10) { 0U }
+    arr.usePinned {
+        assertEquals(0U, it.addressOf(0).pointed.value)
+        assertEquals(0U, it.addressOf(9).pointed.value)
+        assertFailsWith<ArrayIndexOutOfBoundsException> {
+            it.addressOf(10)
+        }
+        assertFailsWith<ArrayIndexOutOfBoundsException> {
+            it.addressOf(-1)
+        }
+        assertFailsWith<ArrayIndexOutOfBoundsException> {
+            it.addressOf(Int.MAX_VALUE)
+        }
+        assertFailsWith<ArrayIndexOutOfBoundsException> {
+            it.addressOf(Int.MIN_VALUE)
+        }
+    }
+}
+
+@Test fun pinnedUShortArrayAddressOf() {
+    val arr = UShortArray(10) { 0U }
+    arr.usePinned {
+        assertEquals(0U, it.addressOf(0).pointed.value)
+        assertEquals(0U, it.addressOf(9).pointed.value)
+        assertFailsWith<ArrayIndexOutOfBoundsException> {
+            it.addressOf(10)
+        }
+        assertFailsWith<ArrayIndexOutOfBoundsException> {
+            it.addressOf(-1)
+        }
+        assertFailsWith<ArrayIndexOutOfBoundsException> {
+            it.addressOf(Int.MAX_VALUE)
+        }
+        assertFailsWith<ArrayIndexOutOfBoundsException> {
+            it.addressOf(Int.MIN_VALUE)
+        }
+    }
+}
+
+@Test fun pinnedUIntArrayAddressOf() {
+    val arr = UIntArray(10) { 0U }
+    arr.usePinned {
+        assertEquals(0U, it.addressOf(0).pointed.value)
+        assertEquals(0U, it.addressOf(9).pointed.value)
+        assertFailsWith<ArrayIndexOutOfBoundsException> {
+            it.addressOf(10)
+        }
+        assertFailsWith<ArrayIndexOutOfBoundsException> {
+            it.addressOf(-1)
+        }
+        assertFailsWith<ArrayIndexOutOfBoundsException> {
+            it.addressOf(Int.MAX_VALUE)
+        }
+        assertFailsWith<ArrayIndexOutOfBoundsException> {
+            it.addressOf(Int.MIN_VALUE)
+        }
+    }
+}
+
+@Test fun pinnedULongArrayAddressOf() {
+    val arr = ULongArray(10) { 0U }
+    arr.usePinned {
+        assertEquals(0U, it.addressOf(0).pointed.value)
+        assertEquals(0U, it.addressOf(9).pointed.value)
+        assertFailsWith<ArrayIndexOutOfBoundsException> {
+            it.addressOf(10)
+        }
+        assertFailsWith<ArrayIndexOutOfBoundsException> {
+            it.addressOf(-1)
+        }
+        assertFailsWith<ArrayIndexOutOfBoundsException> {
+            it.addressOf(Int.MAX_VALUE)
+        }
+        assertFailsWith<ArrayIndexOutOfBoundsException> {
+            it.addressOf(Int.MIN_VALUE)
+        }
+    }
+}
+
+@Test fun pinnedFloatArrayAddressOf() {
+    val arr = FloatArray(10) { 0.0f }
+    arr.usePinned {
+        assertEquals(0.0f, it.addressOf(0).pointed.value)
+        assertEquals(0.0f, it.addressOf(9).pointed.value)
+        assertFailsWith<ArrayIndexOutOfBoundsException> {
+            it.addressOf(10)
+        }
+        assertFailsWith<ArrayIndexOutOfBoundsException> {
+            it.addressOf(-1)
+        }
+        assertFailsWith<ArrayIndexOutOfBoundsException> {
+            it.addressOf(Int.MAX_VALUE)
+        }
+        assertFailsWith<ArrayIndexOutOfBoundsException> {
+            it.addressOf(Int.MIN_VALUE)
+        }
+    }
+}
+
+@Test fun pinnedDoubleArrayAddressOf() {
+    val arr = DoubleArray(10) { 0.0 }
+    arr.usePinned {
+        assertEquals(0.0, it.addressOf(0).pointed.value)
+        assertEquals(0.0, it.addressOf(9).pointed.value)
+        assertFailsWith<ArrayIndexOutOfBoundsException> {
+            it.addressOf(10)
+        }
+        assertFailsWith<ArrayIndexOutOfBoundsException> {
+            it.addressOf(-1)
+        }
+        assertFailsWith<ArrayIndexOutOfBoundsException> {
+            it.addressOf(Int.MAX_VALUE)
+        }
+        assertFailsWith<ArrayIndexOutOfBoundsException> {
+            it.addressOf(Int.MIN_VALUE)
+        }
+    }
+}
diff --git a/backend.native/tests/runtime/collections/array5.kt b/backend.native/tests/runtime/collections/array5.kt
new file mode 100644
index 00000000000..8cc1b18fab1
--- /dev/null
+++ b/backend.native/tests/runtime/collections/array5.kt
@@ -0,0 +1,969 @@
+/*
+ * Copyright 2010-2020 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license
+ * that can be found in the LICENSE file.
+ */
+
+package runtime.collections.array5
+
+import kotlin.test.*
+import kotlinx.cinterop.*
+
+@Test fun arrayGet() {
+    val arr = Array(10) { 0 }
+    assertEquals(0, arr[0])
+    assertEquals(0, arr[9])
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr[10]
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr[-1]
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr[Int.MAX_VALUE]
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr[Int.MIN_VALUE]
+    }
+}
+
+@Test fun arraySet() {
+    val arr = Array(10) { 0 }
+    arr[0] = 1
+    arr[9] = 1
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr[10] = 1
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr[-1] = 1
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr[Int.MAX_VALUE] = 1
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr[Int.MIN_VALUE] = 1
+    }
+}
+
+@Test fun byteArrayGet() {
+    val arr = ByteArray(10) { 0 }
+    assertEquals(0, arr[0])
+    assertEquals(0, arr[9])
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr[10]
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr[-1]
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr[Int.MAX_VALUE]
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr[Int.MIN_VALUE]
+    }
+}
+
+@Test fun byteArraySet() {
+    val arr = ByteArray(10) { 0 }
+    arr[0] = 1
+    arr[9] = 1
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr[10] = 1
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr[-1] = 1
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr[Int.MAX_VALUE] = 1
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr[Int.MIN_VALUE] = 1
+    }
+}
+
+@Test fun uByteArrayGet() {
+    val arr = UByteArray(10) { 0U }
+    assertEquals(0U, arr[0])
+    assertEquals(0U, arr[9])
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr[10]
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr[-1]
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr[Int.MAX_VALUE]
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr[Int.MIN_VALUE]
+    }
+}
+
+@Test fun uByteArraySet() {
+    val arr = UByteArray(10) { 0U }
+    arr[0] = 1U
+    arr[9] = 1U
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr[10] = 1U
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr[-1] = 1U
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr[Int.MAX_VALUE] = 1U
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr[Int.MIN_VALUE] = 1U
+    }
+}
+
+@Test fun shortArrayGet() {
+    val arr = ShortArray(10) { 0 }
+    assertEquals(0, arr[0])
+    assertEquals(0, arr[9])
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr[10]
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr[-1]
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr[Int.MAX_VALUE]
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr[Int.MIN_VALUE]
+    }
+}
+
+@Test fun shortArraySet() {
+    val arr = ShortArray(10) { 0 }
+    arr[0] = 1
+    arr[9] = 1
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr[10] = 1
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr[-1] = 1
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr[Int.MAX_VALUE] = 1
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr[Int.MIN_VALUE] = 1
+    }
+}
+
+@Test fun uShortArrayGet() {
+    val arr = UShortArray(10) { 0U }
+    assertEquals(0U, arr[0])
+    assertEquals(0U, arr[9])
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr[10]
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr[-1]
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr[Int.MAX_VALUE]
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr[Int.MIN_VALUE]
+    }
+}
+
+@Test fun uShortArraySet() {
+    val arr = UShortArray(10) { 0U }
+    arr[0] = 1U
+    arr[9] = 1U
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr[10] = 1U
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr[-1] = 1U
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr[Int.MAX_VALUE] = 1U
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr[Int.MIN_VALUE] = 1U
+    }
+}
+
+@Test fun intArrayGet() {
+    val arr = IntArray(10) { 0 }
+    assertEquals(0, arr[0])
+    assertEquals(0, arr[9])
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr[10]
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr[-1]
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr[Int.MAX_VALUE]
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr[Int.MIN_VALUE]
+    }
+}
+
+@Test fun intArraySet() {
+    val arr = IntArray(10) { 0 }
+    arr[0] = 1
+    arr[9] = 1
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr[10] = 1
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr[-1] = 1
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr[Int.MAX_VALUE] = 1
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr[Int.MIN_VALUE] = 1
+    }
+}
+
+@Test fun uIntArrayGet() {
+    val arr = UIntArray(10) { 0U }
+    assertEquals(0U, arr[0])
+    assertEquals(0U, arr[9])
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr[10]
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr[-1]
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr[Int.MAX_VALUE]
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr[Int.MIN_VALUE]
+    }
+}
+
+@Test fun uIntArraySet() {
+    val arr = UIntArray(10) { 0U }
+    arr[0] = 1U
+    arr[9] = 1U
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr[10] = 1U
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr[-1] = 1U
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr[Int.MAX_VALUE] = 1U
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr[Int.MIN_VALUE] = 1U
+    }
+}
+
+@Test fun longArrayGet() {
+    val arr = LongArray(10) { 0 }
+    assertEquals(0, arr[0])
+    assertEquals(0, arr[9])
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr[10]
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr[-1]
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr[Int.MAX_VALUE]
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr[Int.MIN_VALUE]
+    }
+}
+
+@Test fun longArraySet() {
+    val arr = LongArray(10) { 0 }
+    arr[0] = 1
+    arr[9] = 1
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr[10] = 1
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr[-1] = 1
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr[Int.MAX_VALUE] = 1
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr[Int.MIN_VALUE] = 1
+    }
+}
+
+@Test fun uLongArrayGet() {
+    val arr = ULongArray(10) { 0U }
+    assertEquals(0U, arr[0])
+    assertEquals(0U, arr[9])
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr[10]
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr[-1]
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr[Int.MAX_VALUE]
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr[Int.MIN_VALUE]
+    }
+}
+
+@Test fun uLongArraySet() {
+    val arr = ULongArray(10) { 0U }
+    arr[0] = 1U
+    arr[9] = 1U
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr[10] = 1U
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr[-1] = 1U
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr[Int.MAX_VALUE] = 1U
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr[Int.MIN_VALUE] = 1U
+    }
+}
+
+@Test fun floatArrayGet() {
+    val arr = FloatArray(10) { 0.0f }
+    assertEquals(0.0f, arr[0])
+    assertEquals(0.0f, arr[9])
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr[10]
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr[-1]
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr[Int.MAX_VALUE]
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr[Int.MIN_VALUE]
+    }
+}
+
+@Test fun floatArraySet() {
+    val arr = FloatArray(10) { 0.0f }
+    arr[0] = 1.0f
+    arr[9] = 1.0f
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr[10] = 1.0f
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr[-1] = 1.0f
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr[Int.MAX_VALUE] = 1.0f
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr[Int.MIN_VALUE] = 1.0f
+    }
+}
+
+@Test fun doubleArrayGet() {
+    val arr = DoubleArray(10) { 0.0 }
+    assertEquals(0.0, arr[0])
+    assertEquals(0.0, arr[9])
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr[10]
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr[-1]
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr[Int.MAX_VALUE]
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr[Int.MIN_VALUE]
+    }
+}
+
+@Test fun doubleArraySet() {
+    val arr = DoubleArray(10) { 0.0 }
+    arr[0] = 1.0
+    arr[9] = 1.0
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr[10] = 1.0
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr[-1] = 1.0
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr[Int.MAX_VALUE] = 1.0
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr[Int.MIN_VALUE] = 1.0
+    }
+}
+
+@Test fun booleanArrayGet() {
+    val arr = BooleanArray(10) { false }
+    assertEquals(false, arr[0])
+    assertEquals(false, arr[9])
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr[10]
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr[-1]
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr[Int.MAX_VALUE]
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr[Int.MIN_VALUE]
+    }
+}
+
+@Test fun booleanArraySet() {
+    val arr = BooleanArray(10) { false }
+    arr[0] = true
+    arr[9] = true
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr[10] = true
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr[-1] = true
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr[Int.MAX_VALUE] = true
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr[Int.MIN_VALUE] = true
+    }
+}
+
+@Test fun charArrayGet() {
+    val arr = CharArray(10) { '0' }
+    assertEquals('0', arr[0])
+    assertEquals('0', arr[9])
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr[10]
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr[-1]
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr[Int.MAX_VALUE]
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr[Int.MIN_VALUE]
+    }
+}
+
+@Test fun charArraySet() {
+    val arr = CharArray(10) { '0' }
+    arr[0] = '1'
+    arr[9] = '1'
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr[10] = '1'
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr[-1] = '1'
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr[Int.MAX_VALUE] = '1'
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr[Int.MIN_VALUE] = '1'
+    }
+}
+
+@Test fun byteArrayGetUByte() {
+    val arr = ByteArray(10) { 0 }
+    assertEquals(0U, arr.getUByteAt(0))
+    assertEquals(0U, arr.getUByteAt(9))
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr.getUByteAt(10)
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr.getUByteAt(-1)
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr.getUByteAt(Int.MAX_VALUE)
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr.getUByteAt(Int.MIN_VALUE)
+    }
+}
+
+@Test fun byteArraySetUByte() {
+    val arr = ByteArray(10) { 0 }
+    arr.setUByteAt(0, 1U)
+    arr.setUByteAt(9, 1U)
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr.setUByteAt(10, 1U)
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr.setUByteAt(-1, 1U)
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr.setUByteAt(Int.MAX_VALUE, 1U)
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr.setUByteAt(Int.MIN_VALUE, 1U)
+    }
+}
+
+@Test fun byteArrayGetChar() {
+    val arr = ByteArray(10) { 0 }
+    assertEquals(0.toChar(), arr.getCharAt(0))
+    assertEquals(0.toChar(), arr.getCharAt(8))
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr.getCharAt(9)
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr.getCharAt(10)
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr.getCharAt(-1)
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr.getCharAt(Int.MAX_VALUE)
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr.getCharAt(Int.MIN_VALUE)
+    }
+}
+
+@Test fun byteArraySetChar() {
+    val arr = ByteArray(10) { 0 }
+    arr.setCharAt(0, '1')
+    arr.setCharAt(8, '1')
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr.setCharAt(9, '1')
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr.setCharAt(10, '1')
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr.setCharAt(-1, '1')
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr.setCharAt(Int.MAX_VALUE, '1')
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr.setCharAt(Int.MIN_VALUE, '1')
+    }
+}
+
+@Test fun byteArrayGetShort() {
+    val arr = ByteArray(10) { 0 }
+    assertEquals(0, arr.getShortAt(0))
+    assertEquals(0, arr.getShortAt(8))
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr.getShortAt(9)
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr.getShortAt(10)
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr.getShortAt(-1)
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr.getShortAt(Int.MAX_VALUE)
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr.getShortAt(Int.MIN_VALUE)
+    }
+}
+
+@Test fun byteArraySetShort() {
+    val arr = ByteArray(10) { 0 }
+    arr.setShortAt(0, 0)
+    arr.setShortAt(8, 0)
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr.setShortAt(9, 1)
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr.setShortAt(10, 1)
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr.setShortAt(-1, 1)
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr.setShortAt(Int.MAX_VALUE, 1)
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr.setShortAt(Int.MIN_VALUE, 1)
+    }
+}
+
+@Test fun byteArrayGetUShort() {
+    val arr = ByteArray(10) { 0 }
+    assertEquals(0U, arr.getUShortAt(0))
+    assertEquals(0U, arr.getUShortAt(8))
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr.getUShortAt(9)
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr.getUShortAt(10)
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr.getUShortAt(-1)
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr.getUShortAt(Int.MAX_VALUE)
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr.getUShortAt(Int.MIN_VALUE)
+    }
+}
+
+@Test fun byteArraySetUShort() {
+    val arr = ByteArray(10) { 0 }
+    arr.setUShortAt(0, 0U)
+    arr.setUShortAt(8, 0U)
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr.setUShortAt(9, 1U)
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr.setUShortAt(10, 1U)
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr.setUShortAt(-1, 1U)
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr.setUShortAt(Int.MAX_VALUE, 1U)
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr.setUShortAt(Int.MIN_VALUE, 1U)
+    }
+}
+
+@Test fun byteArrayGetInt() {
+    val arr = ByteArray(10) { 0 }
+    assertEquals(0, arr.getIntAt(0))
+    assertEquals(0, arr.getIntAt(6))
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr.getIntAt(7)
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr.getIntAt(10)
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr.getIntAt(-1)
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr.getIntAt(Int.MAX_VALUE)
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr.getIntAt(Int.MIN_VALUE)
+    }
+}
+
+@Test fun byteArraySetInt() {
+    val arr = ByteArray(10) { 0 }
+    arr.setIntAt(0, 1)
+    arr.setIntAt(6, 1)
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr.setIntAt(7, 1)
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr.setIntAt(10, 1)
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr.setIntAt(-1, 1)
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr.setIntAt(Int.MAX_VALUE, 1)
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr.setIntAt(Int.MIN_VALUE, 1)
+    }
+}
+
+@Test fun byteArrayGetUInt() {
+    val arr = ByteArray(10) { 0 }
+    assertEquals(0U, arr.getUIntAt(0))
+    assertEquals(0U, arr.getUIntAt(6))
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr.getUIntAt(7)
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr.getUIntAt(10)
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr.getUIntAt(-1)
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr.getUIntAt(Int.MAX_VALUE)
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr.getUIntAt(Int.MIN_VALUE)
+    }
+}
+
+@Test fun byteArraySetUInt() {
+    val arr = ByteArray(10) { 0 }
+    arr.setUIntAt(0, 1U)
+    arr.setUIntAt(6, 1U)
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr.setUIntAt(7, 1U)
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr.setUIntAt(10, 1U)
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr.setUIntAt(-1, 1U)
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr.setUIntAt(Int.MAX_VALUE, 1U)
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr.setUIntAt(Int.MIN_VALUE, 1U)
+    }
+}
+
+@Test fun byteArrayGetLong() {
+    val arr = ByteArray(10) { 0 }
+    assertEquals(0, arr.getLongAt(0))
+    assertEquals(0, arr.getLongAt(2))
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr.getLongAt(3)
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr.getLongAt(10)
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr.getLongAt(-1)
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr.getLongAt(Int.MAX_VALUE)
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr.getLongAt(Int.MIN_VALUE)
+    }
+}
+
+@Test fun byteArraySetLong() {
+    val arr = ByteArray(10) { 0 }
+    arr.setLongAt(0, 1)
+    arr.setLongAt(2, 1)
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr.setLongAt(3, 1)
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr.setLongAt(10, 1)
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr.setLongAt(-1, 1)
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr.setLongAt(Int.MAX_VALUE, 1)
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr.setLongAt(Int.MIN_VALUE, 1)
+    }
+}
+
+@Test fun byteArrayGetULong() {
+    val arr = ByteArray(10) { 0 }
+    assertEquals(0U, arr.getULongAt(0))
+    assertEquals(0U, arr.getULongAt(2))
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr.getULongAt(3)
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr.getULongAt(10)
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr.getULongAt(-1)
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr.getULongAt(Int.MAX_VALUE)
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr.getULongAt(Int.MIN_VALUE)
+    }
+}
+
+@Test fun byteArraySetULong() {
+    val arr = ByteArray(10) { 0 }
+    arr.setULongAt(0, 1U)
+    arr.setULongAt(2, 1U)
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr.setULongAt(3, 1U)
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr.setULongAt(10, 1U)
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr.setULongAt(-1, 1U)
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr.setULongAt(Int.MAX_VALUE, 1U)
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr.setULongAt(Int.MIN_VALUE, 1U)
+    }
+}
+
+@Test fun byteArrayGetFloat() {
+    val arr = ByteArray(10) { 0 }
+    assertEquals(0.0f, arr.getFloatAt(0))
+    assertEquals(0.0f, arr.getFloatAt(6))
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr.getFloatAt(7)
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr.getFloatAt(10)
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr.getFloatAt(-1)
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr.getFloatAt(Int.MAX_VALUE)
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr.getFloatAt(Int.MIN_VALUE)
+    }
+}
+
+@Test fun byteArraySetFloat() {
+    val arr = ByteArray(10) { 0 }
+    arr.setFloatAt(0, 1.0f)
+    arr.setFloatAt(6, 1.0f)
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr.setFloatAt(7, 1.0f)
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr.setFloatAt(10, 1.0f)
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr.setFloatAt(-1, 1.0f)
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr.setFloatAt(Int.MAX_VALUE, 1.0f)
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr.setFloatAt(Int.MIN_VALUE, 1.0f)
+    }
+}
+
+@Test fun byteArrayGetDouble() {
+    val arr = ByteArray(10) { 0 }
+    assertEquals(0.0, arr.getDoubleAt(0))
+    assertEquals(0.0, arr.getDoubleAt(2))
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr.getDoubleAt(3)
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr.getDoubleAt(10)
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr.getDoubleAt(-1)
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr.getDoubleAt(Int.MAX_VALUE)
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr.getDoubleAt(Int.MIN_VALUE)
+    }
+}
+
+@Test fun byteArraySetDouble() {
+    val arr = ByteArray(10) { 0 }
+    arr.setDoubleAt(0, 1.0)
+    arr.setDoubleAt(2, 1.0)
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr.setDoubleAt(3, 1.0)
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr.setDoubleAt(10, 1.0)
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr.setDoubleAt(-1, 1.0)
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr.setDoubleAt(Int.MAX_VALUE, 1.0)
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        arr.setDoubleAt(Int.MIN_VALUE, 1.0)
+    }
+}
+
+@Test fun immutableBlobToByteArray() {
+    val blob = immutableBlobOf(0, 0)
+    val arr = blob.toByteArray(0, 1)
+    assertEquals(1, arr.size)
+    assertEquals(0, arr[0])
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        blob.toByteArray(-1, 1)
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        blob.toByteArray(0, -1)
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        blob.toByteArray(0, 10)
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        blob.toByteArray(10, 11)
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        blob.toByteArray(10, 1)
+    }
+}
+
+@Test fun immutableBlobToUByteArray() {
+    val blob = immutableBlobOf(0, 0)
+    val arr = blob.toUByteArray(0, 1)
+    assertEquals(1, arr.size)
+    assertEquals(0U, arr[0])
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        blob.toUByteArray(-1, 1)
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        blob.toUByteArray(0, -1)
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        blob.toUByteArray(0, 10)
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        blob.toUByteArray(10, 11)
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        blob.toUByteArray(10, 1)
+    }
+}
+
+@Test fun immutableBlobAsCPointer() {
+    val blob = immutableBlobOf(0, 0)
+    assertEquals(0, blob.asCPointer(0).pointed.value)
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        blob.asCPointer(10)
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        blob.asCPointer(-1)
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        blob.asCPointer(Int.MAX_VALUE)
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        blob.asCPointer(Int.MIN_VALUE)
+    }
+}
+
+@Test fun immutableBlobAsUCPointer() {
+    val blob = immutableBlobOf(0, 0)
+    assertEquals(0U, blob.asUCPointer(0).pointed.value)
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        blob.asUCPointer(10)
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        blob.asUCPointer(-1)
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        blob.asUCPointer(Int.MAX_VALUE)
+    }
+    assertFailsWith<ArrayIndexOutOfBoundsException> {
+        blob.asUCPointer(Int.MIN_VALUE)
+    }
+}
diff --git a/build-tools/src/main/kotlin/org/jetbrains/kotlin/CompileToBitcode.kt b/build-tools/src/main/kotlin/org/jetbrains/kotlin/CompileToBitcode.kt
index 5b21e2d5a7a..237deaaad7d 100644
--- a/build-tools/src/main/kotlin/org/jetbrains/kotlin/CompileToBitcode.kt
+++ b/build-tools/src/main/kotlin/org/jetbrains/kotlin/CompileToBitcode.kt
@@ -67,7 +67,8 @@ open class CompileToBitcode @Inject constructor(@InputDirectory val srcRoot: Fil
                             "-Werror", "-ftls-model=initial-exec", "-Wno-unused-function")
                 Language.CPP ->
                     listOfNotNull("-std=c++14", "-Werror", "-O2",
-                            "-Wall",
+                            "-Wall", "-Wextra",
+                            "-Wno-unused-parameter",  // False positives with polymorphic functions.
                             "-Wno-unused-function",  // TODO: Enable this warning when we have C++ runtime tests.
                             "-fPIC".takeIf { !HostManager().targetByName(target).isMINGW })
             }
diff --git a/common/src/hash/cpp/Names.cpp b/common/src/hash/cpp/Names.cpp
index 0016f40db82..182eeef3cc7 100644
--- a/common/src/hash/cpp/Names.cpp
+++ b/common/src/hash/cpp/Names.cpp
@@ -29,7 +29,7 @@ constexpr uint32_t PrintableHexSize(uint32_t input_length) {
 
 void PrintableHex(const uint8_t* data, uint32_t data_length, char* hex) {
   static const char* hex_digits = "0123456789ABCDEF";
-  for(int i = 0; i < data_length; ++i) {
+  for (uint32_t i = 0; i < data_length; ++i) {
     *hex++ = hex_digits[(*data >> 4) & 0xf];
     *hex++ = hex_digits[(*data++) & 0xf];
   }
diff --git a/runtime/src/debug/cpp/KDebug.cpp b/runtime/src/debug/cpp/KDebug.cpp
index e990374da5a..a535034522b 100644
--- a/runtime/src/debug/cpp/KDebug.cpp
+++ b/runtime/src/debug/cpp/KDebug.cpp
@@ -113,7 +113,8 @@ int32_t Konan_DebugObjectToUtf8ArrayImpl(KRef obj, char* buffer, int32_t bufferS
   ObjHolder stringHolder;
   auto data = KonanObjectToUtf8Array(obj, stringHolder.slot())->array();
   if (data == nullptr) return 0;
-  KInt toCopy = data->count_ > bufferSize - 1 ? bufferSize - 1 : data->count_;
+  if (bufferSize < 1) return 0;
+  KInt toCopy = data->count_ > static_cast<uint32_t>(bufferSize - 1) ? bufferSize - 1 : data->count_;
   ::memcpy(buffer, ByteArrayAddressOfElementAt(data, 0), toCopy);
   buffer[toCopy] = '\0';
   return toCopy + 1;
@@ -176,7 +177,7 @@ void* Konan_DebugGetFieldAddressImpl(KRef obj, int32_t index) {
     return nullptr;
 
    if (extendedTypeInfo->fieldsCount_ < 0) {
-     if (index > obj->array()->count_)
+     if (static_cast<uint32_t>(index) > obj->array()->count_)
         return nullptr;
 
       int32_t typeIndex = -extendedTypeInfo->fieldsCount_;
diff --git a/runtime/src/debug/cpp/SourceInfo.cpp b/runtime/src/debug/cpp/SourceInfo.cpp
index 4e7f2fb727f..e036ef8ec66 100644
--- a/runtime/src/debug/cpp/SourceInfo.cpp
+++ b/runtime/src/debug/cpp/SourceInfo.cpp
@@ -18,11 +18,11 @@
 
 #ifdef KONAN_CORE_SYMBOLICATION
 #include <KAssert.h>
+#include <cstdint>
 #include <dlfcn.h>
-#include <limits.h>
-#include <stdint.h>
-#include <unistd.h>
+#include <limits>
 #include <string.h>
+#include <unistd.h>
 
 #define TRACE_SYMBOLICATION 0
 #if TRACE_SYMBOLICATION
@@ -51,7 +51,7 @@ typedef struct _CSRange {
 
 typedef unsigned long long CSArchitecture;
 
-#define kCSNow LLONG_MAX
+constexpr auto kCSNow = std::numeric_limits<long long>::max();
 
 namespace {
 
@@ -153,7 +153,8 @@ extern "C" struct SourceInfo Kotlin_getSourceInfo(void* addr) {
      */
     CSSymbolForeachSourceInfo(symbol,
       ^(CSSourceInfoRef ref) {
-        uint32_t lineNumber = CSSourceInfoGetLineNumber(ref);
+        // Expecting CSSourceInfoGetLineNumber not to overflow int32_t max value.
+        int32_t lineNumber = CSSourceInfoGetLineNumber(ref);
         if (lineNumber == 0)
           return 0;
         if (limits.start == -1) {
@@ -170,7 +171,8 @@ extern "C" struct SourceInfo Kotlin_getSourceInfo(void* addr) {
 
     CSSymbolForeachSourceInfo(symbol,
       ^(CSSourceInfoRef ref) {
-          uint32_t lineNumber = CSSourceInfoGetLineNumber(ref);
+          // Expecting CSSourceInfoGetLineNumber not to overflow int32_t max value.
+          int32_t lineNumber = CSSourceInfoGetLineNumber(ref);
           if (lineNumber == 0)
             return 0;
           SYM_DUMP(ref);
diff --git a/runtime/src/launcher/cpp/androidLauncher.cpp b/runtime/src/launcher/cpp/androidLauncher.cpp
index 16348390a80..ebbd8a4d636 100644
--- a/runtime/src/launcher/cpp/androidLauncher.cpp
+++ b/runtime/src/launcher/cpp/androidLauncher.cpp
@@ -143,13 +143,13 @@ void onStart(ANativeActivity* activity) {
 
 void onResume(ANativeActivity* activity) {
   LOGV("onResume called");
-  NativeActivitySaveStateEvent event = { RESUME };
+  NativeActivitySaveStateEvent event = { RESUME, nullptr, 0 };
   putEventSynchronously(&event);
 }
 
 void* onSaveInstanceState(ANativeActivity* activity, size_t* outLen) {
   LOGV("onSaveInstanceState called");
-  NativeActivitySaveStateEvent event = { SAVE_INSTANCE_STATE };
+  NativeActivitySaveStateEvent event = { SAVE_INSTANCE_STATE, nullptr, 0 };
   putEventSynchronously(&event);
   *outLen = event.savedStateSize;
   return event.savedState;
diff --git a/runtime/src/main/cpp/Arrays.cpp b/runtime/src/main/cpp/Arrays.cpp
index 7d0e622d62a..a8d7b3c0659 100644
--- a/runtime/src/main/cpp/Arrays.cpp
+++ b/runtime/src/main/cpp/Arrays.cpp
@@ -34,6 +34,15 @@ ALWAYS_INLINE inline void mutabilityCheck(KConstRef thiz) {
   }
 }
 
+ALWAYS_INLINE inline void boundsCheck(const ArrayHeader* array, KInt index) {
+  // We couldn't have created an array bigger than max KInt value.
+  // So if index is < 0, conversion to an unsigned value would make it bigger
+  // than the array size.
+  if (static_cast<uint32_t>(index) >= array->count_) {
+    ThrowArrayIndexOutOfBoundsException();
+  }
+}
+
 template<typename T>
 inline void fillImpl(KRef thiz, KInt fromIndex, KInt toIndex, T value) {
   ArrayHeader* array = thiz->array();
@@ -65,9 +74,7 @@ inline void copyImpl(KConstRef thiz, KInt fromIndex,
 template <class T>
 inline void PrimitiveArraySet(KRef thiz, KInt index, T value) {
   ArrayHeader* array = thiz->array();
-  if (static_cast<uint32_t>(index) >= array->count_) {
-    ThrowArrayIndexOutOfBoundsException();
-  }
+  boundsCheck(array, index);
   mutabilityCheck(thiz);
   *PrimitiveArrayAddressOfElementAt<T>(array, index) = value;
 }
@@ -75,9 +82,7 @@ inline void PrimitiveArraySet(KRef thiz, KInt index, T value) {
 template <class T>
 inline T PrimitiveArrayGet(KConstRef thiz, KInt index) {
   const ArrayHeader* array = thiz->array();
-  if (static_cast<uint32_t>(index) >= array->count_) {
-    ThrowArrayIndexOutOfBoundsException();
-  }
+  boundsCheck(array, index);
   return *PrimitiveArrayAddressOfElementAt<T>(array, index);
 }
 
@@ -93,17 +98,13 @@ extern const ObjHeader theEmptyArray;
 // Array.kt
 OBJ_GETTER(Kotlin_Array_get, KConstRef thiz, KInt index) {
   const ArrayHeader* array = thiz->array();
-  if (static_cast<uint32_t>(index) >= array->count_) {
-    ThrowArrayIndexOutOfBoundsException();
-  }
+  boundsCheck(array, index);
   RETURN_OBJ(*ArrayAddressOfElementAt(array, index));
 }
 
 void Kotlin_Array_set(KRef thiz, KInt index, KConstRef value) {
   ArrayHeader* array = thiz->array();
-  if (static_cast<uint32_t>(index) >= array->count_) {
-    ThrowArrayIndexOutOfBoundsException();
-  }
+  boundsCheck(array, index);
   mutabilityCheck(thiz);
   UpdateHeapRef(ArrayAddressOfElementAt(array, index), value);
 }
@@ -128,7 +129,7 @@ void Kotlin_Array_copyImpl(KConstRef thiz, KInt fromIndex,
   ArrayHeader* destinationArray = destination->array();
   if (count < 0 ||
       fromIndex < 0 || static_cast<uint32_t>(count) + fromIndex > array->count_ ||
-      toIndex < 0 || static_cast<uint32_t>(count)+ toIndex > destinationArray->count_) {
+      toIndex < 0 || static_cast<uint32_t>(count) + toIndex > destinationArray->count_) {
     ThrowArrayIndexOutOfBoundsException();
   }
   mutabilityCheck(destination);
@@ -152,17 +153,13 @@ OBJ_GETTER0(Kotlin_emptyArray) {
 
 KByte Kotlin_ByteArray_get(KConstRef thiz, KInt index) {
   const ArrayHeader* array = thiz->array();
-  if (static_cast<uint32_t>(index) >= array->count_) {
-    ThrowArrayIndexOutOfBoundsException();
-  }
+  boundsCheck(array, index);
   return *ByteArrayAddressOfElementAt(array, index);
 }
 
 void Kotlin_ByteArray_set(KRef thiz, KInt index, KByte value) {
   ArrayHeader* array = thiz->array();
-  if (static_cast<uint32_t>(index) >= array->count_) {
-    ThrowArrayIndexOutOfBoundsException();
-  }
+  boundsCheck(array, index);
   mutabilityCheck(thiz);
   *ByteArrayAddressOfElementAt(array, index) = value;
 }
@@ -174,7 +171,7 @@ KInt Kotlin_ByteArray_getArrayLength(KConstRef thiz) {
 
 KChar Kotlin_ByteArray_getCharAt(KConstRef thiz, KInt index) {
   const ArrayHeader* array = thiz->array();
-  if (static_cast<uint32_t>(index + 1) >= array->count_) {
+  if (index < 0 || static_cast<uint32_t>(index) + 1 >= array->count_) {
     ThrowArrayIndexOutOfBoundsException();
   }
 #if KONAN_NO_UNALIGNED_ACCESS
@@ -192,7 +189,7 @@ KChar Kotlin_ByteArray_getCharAt(KConstRef thiz, KInt index) {
 
 KShort Kotlin_ByteArray_getShortAt(KConstRef thiz, KInt index) {
   const ArrayHeader* array = thiz->array();
-  if (static_cast<uint32_t>(index + 1) >= array->count_) {
+  if (index < 0 || static_cast<uint32_t>(index) + 1 >= array->count_) {
     ThrowArrayIndexOutOfBoundsException();
   }
 #if KONAN_NO_UNALIGNED_ACCESS
@@ -210,7 +207,7 @@ KShort Kotlin_ByteArray_getShortAt(KConstRef thiz, KInt index) {
 
 KInt Kotlin_ByteArray_getIntAt(KConstRef thiz, KInt index) {
   const ArrayHeader* array = thiz->array();
-  if (static_cast<uint32_t>(index + 3) >= array->count_) {
+  if (index < 0 || static_cast<uint32_t>(index) + 3 >= array->count_) {
     ThrowArrayIndexOutOfBoundsException();
   }
 #if KONAN_NO_UNALIGNED_ACCESS
@@ -229,7 +226,7 @@ KInt Kotlin_ByteArray_getIntAt(KConstRef thiz, KInt index) {
 
 KLong Kotlin_ByteArray_getLongAt(KConstRef thiz, KInt index) {
   const ArrayHeader* array = thiz->array();
-  if (static_cast<uint32_t>(index + 7) >= array->count_) {
+  if (index < 0 || static_cast<uint32_t>(index) + 7 >= array->count_) {
     ThrowArrayIndexOutOfBoundsException();
   }
 #if KONAN_NO_UNALIGNED_ACCESS
@@ -250,7 +247,7 @@ KLong Kotlin_ByteArray_getLongAt(KConstRef thiz, KInt index) {
 
 KFloat Kotlin_ByteArray_getFloatAt(KConstRef thiz, KInt index) {
   const ArrayHeader* array = thiz->array();
-  if (static_cast<uint32_t>(index + 3) >= array->count_) {
+  if (index < 0 || static_cast<uint32_t>(index) + 3 >= array->count_) {
     ThrowArrayIndexOutOfBoundsException();
   }
 #if KONAN_NO_UNALIGNED_ACCESS
@@ -279,7 +276,7 @@ KFloat Kotlin_ByteArray_getFloatAt(KConstRef thiz, KInt index) {
 
 KDouble Kotlin_ByteArray_getDoubleAt(KConstRef thiz, KInt index) {
   const ArrayHeader* array = thiz->array();
-  if (static_cast<uint32_t>(index + 7) >= array->count_) {
+  if (index < 0 || static_cast<uint32_t>(index) + 7 >= array->count_) {
     ThrowArrayIndexOutOfBoundsException();
   }
 #if KONAN_NO_UNALIGNED_ACCESS
@@ -315,7 +312,7 @@ KDouble Kotlin_ByteArray_getDoubleAt(KConstRef thiz, KInt index) {
 
 void Kotlin_ByteArray_setCharAt(KRef thiz, KInt index, KChar value) {
   ArrayHeader* array = thiz->array();
-  if (static_cast<uint32_t>(index + 1) >= array->count_) {
+  if (index < 0 || static_cast<uint32_t>(index) + 1 >= array->count_) {
     ThrowArrayIndexOutOfBoundsException();
   }
   mutabilityCheck(thiz);
@@ -333,7 +330,7 @@ void Kotlin_ByteArray_setCharAt(KRef thiz, KInt index, KChar value) {
 
 void Kotlin_ByteArray_setShortAt(KRef thiz, KInt index, KShort value) {
   ArrayHeader* array = thiz->array();
-  if (static_cast<uint32_t>(index + 1) >= array->count_) {
+  if (index < 0 || static_cast<uint32_t>(index) + 1 >= array->count_) {
     ThrowArrayIndexOutOfBoundsException();
   }
   mutabilityCheck(thiz);
@@ -351,7 +348,7 @@ void Kotlin_ByteArray_setShortAt(KRef thiz, KInt index, KShort value) {
 
 void Kotlin_ByteArray_setIntAt(KRef thiz, KInt index, KInt value) {
   ArrayHeader* array = thiz->array();
-  if (static_cast<uint32_t>(index + 3) >= array->count_) {
+  if (index < 0 || static_cast<uint32_t>(index) + 3 >= array->count_) {
     ThrowArrayIndexOutOfBoundsException();
   }
   mutabilityCheck(thiz);
@@ -371,7 +368,7 @@ void Kotlin_ByteArray_setIntAt(KRef thiz, KInt index, KInt value) {
 
 void Kotlin_ByteArray_setLongAt(KRef thiz, KInt index, KLong value) {
   ArrayHeader* array = thiz->array();
-  if (static_cast<uint32_t>(index + 7) >= array->count_) {
+  if (index < 0 || static_cast<uint32_t>(index) + 7 >= array->count_) {
     ThrowArrayIndexOutOfBoundsException();
   }
   mutabilityCheck(thiz);
@@ -395,7 +392,7 @@ void Kotlin_ByteArray_setLongAt(KRef thiz, KInt index, KLong value) {
 
 void Kotlin_ByteArray_setFloatAt(KRef thiz, KInt index, KFloat value) {
   ArrayHeader* array = thiz->array();
-  if (static_cast<uint32_t>(index + 3) >= array->count_) {
+  if (index < 0 || static_cast<uint32_t>(index) + 3 >= array->count_) {
     ThrowArrayIndexOutOfBoundsException();
   }
   mutabilityCheck(thiz);
@@ -417,7 +414,7 @@ void Kotlin_ByteArray_setFloatAt(KRef thiz, KInt index, KFloat value) {
 
 void Kotlin_ByteArray_setDoubleAt(KRef thiz, KInt index, KDouble value) {
   ArrayHeader* array = thiz->array();
-  if (static_cast<uint32_t>(index + 7) >= array->count_) {
+  if (index < 0 || static_cast<uint32_t>(index) + 7 >= array->count_) {
     ThrowArrayIndexOutOfBoundsException();
   }
   mutabilityCheck(thiz);
@@ -455,7 +452,7 @@ OBJ_GETTER(Kotlin_CharArray_copyOf, KConstRef thiz, KInt newSize) {
     ThrowIllegalArgumentException();
   }
   ArrayHeader* result = AllocArrayInstance(array->type_info(), newSize, OBJ_RESULT)->array();
-  KInt toCopy = array->count_ < newSize ?  array->count_ : newSize;
+  KInt toCopy = array->count_ < static_cast<uint32_t>(newSize) ?  array->count_ : newSize;
   memcpy(
       PrimitiveArrayAddressOfElementAt<KChar>(result, 0),
       PrimitiveArrayAddressOfElementAt<KChar>(array, 0),
@@ -633,8 +630,8 @@ KInt Kotlin_NativePtrArray_getArrayLength(KConstRef thiz) {
 
 OBJ_GETTER(Kotlin_ImmutableBlob_toByteArray, KConstRef thiz, KInt startIndex, KInt endIndex) {
   const ArrayHeader* array = thiz->array();
-  if (startIndex < 0 || endIndex > array->count_ || startIndex > endIndex) {
-      ThrowArrayIndexOutOfBoundsException();
+  if (startIndex < 0 || static_cast<uint32_t>(endIndex) > array->count_ || startIndex > endIndex) {
+    ThrowArrayIndexOutOfBoundsException();
   }
   KInt count = endIndex - startIndex;
   ArrayHeader* result = AllocArrayInstance(theByteArrayTypeInfo, count, OBJ_RESULT)->array();
@@ -646,23 +643,26 @@ OBJ_GETTER(Kotlin_ImmutableBlob_toByteArray, KConstRef thiz, KInt startIndex, KI
 
 KNativePtr Kotlin_ImmutableBlob_asCPointerImpl(KRef thiz, KInt offset) {
   ArrayHeader* array = thiz->array();
-  if (offset < 0 || offset > array->count_)  {
-        ThrowArrayIndexOutOfBoundsException();
+  // We couldn't have created an array bigger than max KInt value.
+  // So if index is < 0, conversion to an unsigned value would make it bigger
+  // than the array size.
+  if (static_cast<uint32_t>(offset) > array->count_)  {
+    ThrowArrayIndexOutOfBoundsException();
   }
   return PrimitiveArrayAddressOfElementAt<KByte>(array, offset);
 }
 
 KNativePtr Kotlin_Arrays_getByteArrayAddressOfElement(KRef thiz, KInt index) {
   ArrayHeader* array = thiz->array();
-  if (index < 0 || index >= array->count_) {
-    ThrowArrayIndexOutOfBoundsException();
-  }
+  boundsCheck(array, index);
 
   return AddressOfElementAt<KByte>(array, index);
 }
 
 KNativePtr Kotlin_Arrays_getCharArrayAddressOfElement (KRef thiz, KInt index) {
   ArrayHeader* array = thiz->array();
+  boundsCheck(array, index);
+
   return CharArrayAddressOfElementAt(array, index);
 }
 
@@ -672,45 +672,35 @@ KNativePtr Kotlin_Arrays_getStringAddressOfElement (KRef thiz, KInt index) {
 
 KNativePtr Kotlin_Arrays_getShortArrayAddressOfElement(KRef thiz, KInt index) {
   ArrayHeader* array = thiz->array();
-  if (index < 0 || index >= array->count_) {
-    ThrowArrayIndexOutOfBoundsException();
-  }
+  boundsCheck(array, index);
 
   return AddressOfElementAt<KShort>(array, index);
 }
 
 KNativePtr Kotlin_Arrays_getIntArrayAddressOfElement(KRef thiz, KInt index) {
   ArrayHeader* array = thiz->array();
-  if (index < 0 || index >= array->count_) {
-    ThrowArrayIndexOutOfBoundsException();
-  }
+  boundsCheck(array, index);
 
   return AddressOfElementAt<KInt>(array, index);
 }
 
 KNativePtr Kotlin_Arrays_getLongArrayAddressOfElement(KRef thiz, KInt index) {
   ArrayHeader* array = thiz->array();
-  if (index < 0 || index >= array->count_) {
-    ThrowArrayIndexOutOfBoundsException();
-  }
+  boundsCheck(array, index);
 
   return AddressOfElementAt<KLong>(array, index);
 }
 
 KNativePtr Kotlin_Arrays_getFloatArrayAddressOfElement(KRef thiz, KInt index) {
   ArrayHeader* array = thiz->array();
-  if (index < 0 || index >= array->count_) {
-    ThrowArrayIndexOutOfBoundsException();
-  }
+  boundsCheck(array, index);
 
   return AddressOfElementAt<KFloat>(array, index);
 }
 
 KNativePtr Kotlin_Arrays_getDoubleArrayAddressOfElement(KRef thiz, KInt index) {
   ArrayHeader* array = thiz->array();
-  if (index < 0 || index >= array->count_) {
-    ThrowArrayIndexOutOfBoundsException();
-  }
+  boundsCheck(array, index);
 
   return AddressOfElementAt<KDouble>(array, index);
 }
diff --git a/runtime/src/main/cpp/CyclicCollector.cpp b/runtime/src/main/cpp/CyclicCollector.cpp
index 08f7660d723..800ba285e64 100644
--- a/runtime/src/main/cpp/CyclicCollector.cpp
+++ b/runtime/src/main/cpp/CyclicCollector.cpp
@@ -96,7 +96,7 @@ inline void traverseObjectFields(ObjHeader* obj, func process) {
     }
   } else {
     ArrayHeader* array = obj->array();
-    for (int index = 0; index < array->count_; index++) {
+    for (uint32_t index = 0; index < array->count_; index++) {
       process(ArrayAddressOfElementAt(array, index));
     }
   }
@@ -242,7 +242,7 @@ class CyclicCollector {
              RuntimeAssert(objContainer->frozen(), "Must be frozen aggregate");
              ContainerHeader** subContainer = reinterpret_cast<ContainerHeader**>(objContainer + 1);
              refCount = 0;
-             for (int i = 0; i < objContainer->objectCount(); ++i) {
+             for (uint32_t i = 0; i < objContainer->objectCount(); ++i) {
                  auto* componentObj = reinterpret_cast<ObjHeader*>((*subContainer) + 1);
                  refCount += sideRefCounts[componentObj];
                  subContainer++;
diff --git a/runtime/src/main/cpp/Exceptions.cpp b/runtime/src/main/cpp/Exceptions.cpp
index 6ae34e90756..88e282d6140 100644
--- a/runtime/src/main/cpp/Exceptions.cpp
+++ b/runtime/src/main/cpp/Exceptions.cpp
@@ -161,7 +161,7 @@ OBJ_GETTER(GetStackTraceStrings, KConstRef stackTrace) {
   ObjHolder resultHolder;
   ObjHeader* strings = AllocArrayInstance(theArrayTypeInfo, size, resultHolder.slot());
 #if USE_GCC_UNWIND
-  for (int index = 0; index < size; ++index) {
+  for (uint32_t index = 0; index < size; ++index) {
     KNativePtr address = Kotlin_NativePtrArray_get(stackTrace, index);
     char symbol[512];
     if (!AddressToSymbol((const void*) address, symbol, sizeof(symbol))) {
@@ -179,7 +179,7 @@ OBJ_GETTER(GetStackTraceStrings, KConstRef stackTrace) {
     char **symbols = backtrace_symbols(PrimitiveArrayAddressOfElementAt<KNativePtr>(stackTrace->array(), 0), size);
     RuntimeCheck(symbols != nullptr, "Not enough memory to retrieve the stacktrace");
 
-    for (int index = 0; index < size; ++index) {
+    for (uint32_t index = 0; index < size; ++index) {
       auto sourceInfo = getSourceInfo(stackTrace, index);
       const char* symbol = symbols[index];
       const char* result;
diff --git a/runtime/src/main/cpp/ExecFormat.cpp b/runtime/src/main/cpp/ExecFormat.cpp
index f5bd74669dd..d9f71f54417 100644
--- a/runtime/src/main/cpp/ExecFormat.cpp
+++ b/runtime/src/main/cpp/ExecFormat.cpp
@@ -153,7 +153,7 @@ extern "C" bool AddressToSymbol(const void* address, char* resultBuffer, size_t
 namespace {
 
 static void* mapModuleFile(HMODULE hModule) {
-  int bufferLength = 64;
+  DWORD bufferLength = 64;
   wchar_t* buffer = nullptr;
   for (;;) {
     auto newBuffer = (wchar_t*)konanAllocMemory(sizeof(wchar_t) * bufferLength);
diff --git a/runtime/src/main/cpp/KString.cpp b/runtime/src/main/cpp/KString.cpp
index a0658880b9f..bcfcedd7628 100644
--- a/runtime/src/main/cpp/KString.cpp
+++ b/runtime/src/main/cpp/KString.cpp
@@ -13,6 +13,8 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
+
+#include <limits>
 #include <string.h>
 
 #include "KAssert.h"
@@ -734,12 +736,12 @@ OBJ_GETTER(Kotlin_String_replace, KString thiz, KChar oldChar, KChar newChar, KB
   KChar* resultRaw = CharArrayAddressOfElementAt(result, 0);
   if (ignoreCase) {
     KChar oldCharLower = towlower_Konan(oldChar);
-    for (KInt index = 0; index < count; ++index) {
+    for (uint32_t index = 0; index < count; ++index) {
       KChar thizChar = *thizRaw++;
       *resultRaw++ = towlower_Konan(thizChar) == oldCharLower ? newChar : thizChar;
     }
   } else {
-    for (KInt index = 0; index < count; ++index) {
+    for (uint32_t index = 0; index < count; ++index) {
       KChar thizChar = *thizRaw++;
       *resultRaw++ = thizChar == oldChar ? newChar : thizChar;
     }
@@ -752,8 +754,11 @@ OBJ_GETTER(Kotlin_String_plusImpl, KString thiz, KString other) {
   RuntimeAssert(other != nullptr, "other cannot be null");
   RuntimeAssert(thiz->type_info() == theStringTypeInfo, "Must be a string");
   RuntimeAssert(other->type_info() == theStringTypeInfo, "Must be a string");
-  KInt result_length = thiz->count_ + other->count_;
-  if (result_length < thiz->count_ || result_length < other->count_) {
+  RuntimeAssert(thiz->count_ <= static_cast<uint32_t>(std::numeric_limits<int32_t>::max()), "this cannot be this large");
+  RuntimeAssert(other->count_ <= static_cast<uint32_t>(std::numeric_limits<int32_t>::max()), "other cannot be this large");
+  // Since thiz and other sizes are bounded by int32_t max value, their sum cannot exceed uint32_t max value - 1.
+  uint32_t result_length = thiz->count_ + other->count_;
+  if (result_length > static_cast<uint32_t>(std::numeric_limits<int32_t>::max())) {
     ThrowArrayIndexOutOfBoundsException();
   }
   ArrayHeader* result = AllocArrayInstance(theStringTypeInfo, result_length, OBJ_RESULT)->array();
@@ -773,7 +778,7 @@ OBJ_GETTER(Kotlin_String_toUpperCase, KString thiz) {
   ArrayHeader* result = AllocArrayInstance(theStringTypeInfo, count, OBJ_RESULT)->array();
   const KChar* thizRaw = CharArrayAddressOfElementAt(thiz, 0);
   KChar* resultRaw = CharArrayAddressOfElementAt(result, 0);
-  for (KInt index = 0; index < count; ++index) {
+  for (uint32_t index = 0; index < count; ++index) {
     *resultRaw++ = towupper_Konan(*thizRaw++);
   }
   RETURN_OBJ(result->obj());
@@ -784,7 +789,7 @@ OBJ_GETTER(Kotlin_String_toLowerCase, KString thiz) {
   ArrayHeader* result = AllocArrayInstance(theStringTypeInfo, count, OBJ_RESULT)->array();
   const KChar* thizRaw = CharArrayAddressOfElementAt(thiz, 0);
   KChar* resultRaw = CharArrayAddressOfElementAt(result, 0);
-  for (KInt index = 0; index < count; ++index) {
+  for (uint32_t index = 0; index < count; ++index) {
     *resultRaw++ = towlower_Konan(*thizRaw++);
   }
   RETURN_OBJ(result->obj());
@@ -814,7 +819,7 @@ OBJ_GETTER(Kotlin_String_toCharArray, KString string, KInt start, KInt size) {
 }
 
 OBJ_GETTER(Kotlin_String_subSequence, KString thiz, KInt startIndex, KInt endIndex) {
-  if (startIndex < 0 || endIndex > thiz->count_ || startIndex > endIndex) {
+  if (startIndex < 0 || static_cast<uint32_t>(endIndex) > thiz->count_ || startIndex > endIndex) {
     // TODO: is it correct exception?
     ThrowArrayIndexOutOfBoundsException();
   }
@@ -849,7 +854,7 @@ KInt Kotlin_String_compareToIgnoreCase(KString thiz, KConstRef other) {
   auto count = thiz->count_ < otherString->count_ ? thiz->count_ : otherString->count_;
   const KChar* thizRaw = CharArrayAddressOfElementAt(thiz, 0);
   const KChar* otherRaw = CharArrayAddressOfElementAt(otherString, 0);
-  for (KInt index = 0; index < count; ++index) {
+  for (uint32_t index = 0; index < count; ++index) {
     int diff = towlower_Konan(*thizRaw++) - towlower_Konan(*otherRaw++);
     if (diff != 0)
       return diff < 0 ? -1 : 1;
@@ -864,6 +869,9 @@ KInt Kotlin_String_compareToIgnoreCase(KString thiz, KConstRef other) {
 
 
 KChar Kotlin_String_get(KString thiz, KInt index) {
+  // We couldn't have created a string bigger than max KInt value.
+  // So if index is < 0, conversion to an unsigned value would make it bigger
+  // than the array size.
   if (static_cast<uint32_t>(index) >= thiz->count_) {
     ThrowArrayIndexOutOfBoundsException();
   }
@@ -906,8 +914,8 @@ OBJ_GETTER(Kotlin_String_unsafeStringToUtf8OrThrow, KString thiz, KInt start, KI
 
 KInt Kotlin_StringBuilder_insertString(KRef builder, KInt distIndex, KString fromString, KInt sourceIndex, KInt count) {
   auto toArray = builder->array();
-  RuntimeAssert(sourceIndex >= 0 && sourceIndex + count <= fromString->count_, "must be true");
-  RuntimeAssert(distIndex >= 0 && distIndex + count <= toArray->count_, "must be true");
+  RuntimeAssert(sourceIndex >= 0 && static_cast<uint32_t>(sourceIndex + count) <= fromString->count_, "must be true");
+  RuntimeAssert(distIndex >= 0 && static_cast<uint32_t>(distIndex + count) <= toArray->count_, "must be true");
   memcpy(CharArrayAddressOfElementAt(toArray, distIndex),
          CharArrayAddressOfElementAt(fromString, sourceIndex),
          count * sizeof(KChar));
@@ -916,11 +924,11 @@ KInt Kotlin_StringBuilder_insertString(KRef builder, KInt distIndex, KString fro
 
 KInt Kotlin_StringBuilder_insertInt(KRef builder, KInt position, KInt value) {
   auto toArray = builder->array();
-  RuntimeAssert(toArray->count_ >= 11 + position, "must be true");
+  RuntimeAssert(toArray->count_ >= static_cast<uint32_t>(11 + position), "must be true");
   char cstring[12];
   auto length = konan::snprintf(cstring, sizeof(cstring), "%d", value);
   RuntimeAssert(length >= 0, "This should never happen"); // may be overkill
-  RuntimeAssert(length < sizeof(cstring), "Unexpectedly large value"); // Can't be, but this is what sNprintf for
+  RuntimeAssert(static_cast<size_t>(length) < sizeof(cstring), "Unexpectedly large value"); // Can't be, but this is what sNprintf for
   auto* from = &cstring[0];
   auto* to = CharArrayAddressOfElementAt(toArray, position);
   while (*from) {
@@ -951,7 +959,7 @@ KBoolean Kotlin_String_equalsIgnoreCase(KString thiz, KConstRef other) {
   auto count = thiz->count_;
   const KChar* thizRaw = CharArrayAddressOfElementAt(thiz, 0);
   const KChar* otherRaw = CharArrayAddressOfElementAt(otherString, 0);
-  for (KInt index = 0; index < count; ++index) {
+  for (uint32_t index = 0; index < count; ++index) {
     if (towlower_Konan(*thizRaw++) != towlower_Konan(*otherRaw++)) return false;
   }
   return true;
@@ -1072,7 +1080,7 @@ KInt Kotlin_String_indexOfChar(KString thiz, KChar ch, KInt fromIndex) {
   if (fromIndex < 0) {
     fromIndex = 0;
   }
-  if (fromIndex > thiz->count_) {
+  if (static_cast<uint32_t>(fromIndex) > thiz->count_) {
     return -1;
   }
   KInt count = thiz->count_;
@@ -1088,7 +1096,7 @@ KInt Kotlin_String_lastIndexOfChar(KString thiz, KChar ch, KInt fromIndex) {
   if (fromIndex < 0 || thiz->count_ == 0) {
     return -1;
   }
-  if (fromIndex >= thiz->count_) {
+  if (static_cast<uint32_t>(fromIndex) >= thiz->count_) {
     fromIndex = thiz->count_ - 1;
   }
   KInt index = fromIndex;
@@ -1105,10 +1113,10 @@ KInt Kotlin_String_indexOfString(KString thiz, KString other, KInt fromIndex) {
   if (fromIndex < 0) {
     fromIndex = 0;
   }
-  if (fromIndex >= thiz->count_) {
+  if (static_cast<uint32_t>(fromIndex) >= thiz->count_) {
     return (other->count_ == 0) ? thiz->count_ : -1;
   }
-  if (other->count_ > static_cast<KInt>(thiz->count_) - fromIndex) {
+  if (static_cast<KInt>(other->count_) > static_cast<KInt>(thiz->count_) - fromIndex) {
     return -1;
   }
   // An empty string can be always found.
diff --git a/runtime/src/main/cpp/Memory.cpp b/runtime/src/main/cpp/Memory.cpp
index a830b922cc9..0a6967ff2cc 100644
--- a/runtime/src/main/cpp/Memory.cpp
+++ b/runtime/src/main/cpp/Memory.cpp
@@ -102,7 +102,7 @@ constexpr size_t kMaxToFreeSizeThreshold = 8 * 1024;
 // Never exceed this value when increasing size for toFree set, triggering actual cycle collector.
 constexpr size_t kMaxErgonomicToFreeSizeThreshold = 8 * 1024 * 1024;
 // How many elements in finalizer queue allowed before cleaning it up.
-constexpr size_t kFinalizerQueueThreshold = 32;
+constexpr int32_t kFinalizerQueueThreshold = 32;
 // If allocated that much memory since last GC - force new GC.
 constexpr size_t kMaxGcAllocThreshold = 8 * 1024 * 1024;
 // If the ratio of GC collection cycles time to program execution time is greater this value,
@@ -848,7 +848,7 @@ inline void traverseObjectFields(ObjHeader* obj, func process) {
     }
   } else {
     ArrayHeader* array = obj->array();
-    for (int index = 0; index < array->count_; index++) {
+    for (uint32_t index = 0; index < array->count_; index++) {
       process(ArrayAddressOfElementAt(array, index));
     }
   }
@@ -866,7 +866,7 @@ template <typename func>
 inline void traverseContainerObjects(ContainerHeader* container, func process) {
   RuntimeAssert(!isAggregatingFrozenContainer(container), "Must not be called on such containers");
   ObjHeader* obj = reinterpret_cast<ObjHeader*>(container + 1);
-  for (int i = 0; i < container->objectCount(); ++i) {
+  for (uint32_t i = 0; i < container->objectCount(); ++i) {
     process(obj);
     obj = reinterpret_cast<ObjHeader*>(
       reinterpret_cast<uintptr_t>(obj) + objectSize(obj));
@@ -1052,7 +1052,7 @@ void freeAggregatingFrozenContainer(ContainerHeader* container) {
   // Special container for frozen objects.
   ContainerHeader** subContainer = reinterpret_cast<ContainerHeader**>(container + 1);
   MEMORY_LOG("Total subcontainers = %d\n", container->objectCount());
-  for (int i = 0; i < container->objectCount(); ++i) {
+  for (uint32_t i = 0; i < container->objectCount(); ++i) {
     MEMORY_LOG("Freeing subcontainer %p\n", *subContainer);
     freeContainer(*subContainer++);
   }
@@ -1067,7 +1067,7 @@ void freeAggregatingFrozenContainer(ContainerHeader* container) {
 // so better be inlined.
 ALWAYS_INLINE void runDeallocationHooks(ContainerHeader* container) {
   ObjHeader* obj = reinterpret_cast<ObjHeader*>(container + 1);
-  for (int index = 0; index < container->objectCount(); index++) {
+  for (uint32_t index = 0; index < container->objectCount(); index++) {
     auto* type_info = obj->type_info();
     if (type_info == theWorkerBoundReferenceTypeInfo) {
       DisposeWorkerBoundReference(obj);
@@ -1653,7 +1653,7 @@ inline ArenaContainer* initedArena(ObjHeader** auxSlot) {
 inline size_t containerSize(const ContainerHeader* container) {
   size_t result = 0;
   const ObjHeader* obj = reinterpret_cast<const ObjHeader*>(container + 1);
-  for (int object = 0; object < container->objectCount(); object++) {
+  for (uint32_t object = 0; object < container->objectCount(); object++) {
     size_t size = objectSize(obj);
     result += size;
     obj = reinterpret_cast<ObjHeader*>(reinterpret_cast<uintptr_t>(obj) + size);
@@ -1771,7 +1771,8 @@ void garbageCollect(MemoryState* state, bool force) {
   auto decrementStackDuration = konan::getTimeMicros() - decrementStackStartTime;
   GC_LOG("||| GC: decrementStackDuration = %lld\n", decrementStackDuration);
 #endif
-  long stackReferences = afterDecrements - beforeDecrements;
+  RuntimeAssert(afterDecrements >= beforeDecrements, "toRelease size must not have decreased");
+  size_t stackReferences = afterDecrements - beforeDecrements;
   if (state->gcErgonomics && stackReferences * 5 > state->gcThreshold) {
     increaseGcThreshold(state);
     GC_LOG("||| GC: too many stack references, increased threshold to %d\n", state->gcThreshold);
diff --git a/runtime/src/main/cpp/Natives.cpp b/runtime/src/main/cpp/Natives.cpp
index e9fb15336f8..c0e339c5b66 100644
--- a/runtime/src/main/cpp/Natives.cpp
+++ b/runtime/src/main/cpp/Natives.cpp
@@ -14,11 +14,12 @@
  * limitations under the License.
  */
 
-#include <limits.h>
-#include <stdint.h>
-#include <stdlib.h>
-#include <stdio.h>
-#include <string.h>
+#include <cstdint>
+#include <cstdio>
+#include <cstdlib>
+#include <cstring>
+#include <limits>
+#include <type_traits>
 
 #include "KAssert.h"
 #include "Exceptions.h"
@@ -49,7 +50,7 @@ OBJ_GETTER0(Kotlin_native_internal_undefined) {
 }
 
 void* Kotlin_interop_malloc(KLong size, KInt align) {
-  if (size > SIZE_MAX) {
+  if (size < 0 || static_cast<std::make_unsigned<decltype(size)>::type>(size) > std::numeric_limits<size_t>::max()) {
     return nullptr;
   }
   RuntimeAssert(align > 0, "Unsupported alignment");
diff --git a/runtime/src/main/cpp/ObjCExceptions.cpp b/runtime/src/main/cpp/ObjCExceptions.cpp
index ca54e794263..a3c3ebdbec2 100644
--- a/runtime/src/main/cpp/ObjCExceptions.cpp
+++ b/runtime/src/main/cpp/ObjCExceptions.cpp
@@ -22,11 +22,11 @@ static void writeStackTraceToBuffer(KRef throwable, char* buffer, unsigned long
   *(bufferPointer++) = '(';
   --remainingBytes;
 
-  for (int index = 0; index < stackTrace->count_; ++index) {
+  for (uint32_t index = 0; index < stackTrace->count_; ++index) {
     KNativePtr ptr = *PrimitiveArrayAddressOfElementAt<KNativePtr>(stackTrace, index);
     int bytes = snprintf(bufferPointer, remainingBytes, "0x%" PRIxPTR " ", reinterpret_cast<uintptr_t>(ptr));
 
-    if (bytes >= remainingBytes) {
+    if (bytes < 0 || static_cast<unsigned long>(bytes) >= remainingBytes) {
       break;
     }
 
@@ -122,4 +122,4 @@ void ReportBacktraceToIosCrashLog(KRef throwable) {
   writeStackTraceToBuffer(throwable, buffer, bufferSize);
 }
 
-#endif // KONAN_REPORT_BACKTRACE_TO_IOS_CRASH_LOG
\ No newline at end of file
+#endif // KONAN_REPORT_BACKTRACE_TO_IOS_CRASH_LOG
diff --git a/runtime/src/main/cpp/ObjCExport.mm b/runtime/src/main/cpp/ObjCExport.mm
index f1b4df001e5..3eb82795b65 100644
--- a/runtime/src/main/cpp/ObjCExport.mm
+++ b/runtime/src/main/cpp/ObjCExport.mm
@@ -693,7 +693,7 @@ static const TypeInfo* createTypeInfo(
   }
 
   const TypeInfo** implementedInterfaces_ = konanAllocArray<const TypeInfo*>(implementedInterfaces.size());
-  for (int i = 0; i < implementedInterfaces.size(); ++i) {
+  for (size_t i = 0; i < implementedInterfaces.size(); ++i) {
     implementedInterfaces_[i] = implementedInterfaces[i];
   }
 
@@ -709,7 +709,7 @@ static const TypeInfo* createTypeInfo(
   }
 
   MethodTableRecord* openMethods_ = konanAllocArray<MethodTableRecord>(methodTable.size());
-  for (int i = 0; i < methodTable.size(); ++i) openMethods_[i] = methodTable[i];
+  for (size_t i = 0; i < methodTable.size(); ++i) openMethods_[i] = methodTable[i];
 
   result->openMethods_ = openMethods_;
   result->openMethodsCount_ = methodTable.size();
@@ -718,7 +718,7 @@ static const TypeInfo* createTypeInfo(
   result->relativeName_ = nullptr; // TODO: add some info.
   result->writableInfo_ = (WritableTypeInfo*)konanAllocMemory(sizeof(WritableTypeInfo));
 
-  for (int i = 0; i < vtable.size(); ++i) result->vtable()[i] = vtable[i];
+  for (size_t i = 0; i < vtable.size(); ++i) result->vtable()[i] = vtable[i];
 
   return result;
 }
@@ -727,7 +727,7 @@ static void addDefinedSelectors(Class clazz, KStdUnorderedSet<SEL>& result) {
   unsigned int objcMethodCount;
   Method* objcMethods = class_copyMethodList(clazz, &objcMethodCount);
 
-  for (int i = 0; i < objcMethodCount; ++i) {
+  for (unsigned int i = 0; i < objcMethodCount; ++i) {
     result.insert(method_getName(objcMethods[i]));
   }
 
@@ -895,7 +895,7 @@ static const TypeInfo* createTypeInfo(Class clazz, const TypeInfo* superType, co
     auto interfaceVTableIt = interfaceVTables.find(interfaceId);
     RuntimeAssert(interfaceVTableIt != interfaceVTables.end(), "");
     auto& interfaceVTable = interfaceVTableIt->second;
-    RuntimeAssert(methodIndex >= 0 && methodIndex < interfaceVTable.size(), "");
+    RuntimeAssert(methodIndex >= 0 && static_cast<size_t>(methodIndex) < interfaceVTable.size(), "");
     interfaceVTable[methodIndex] = entry;
   };
 
@@ -934,7 +934,7 @@ static const TypeInfo* createTypeInfo(Class clazz, const TypeInfo* superType, co
         interfaceVTables.emplace(interfaceId, KStdVector<VTableElement>(interfaceVTableSize));
       } else {
         auto const& interfaceVTable = interfaceVTablesIt->second;
-        RuntimeAssert(interfaceVTable.size() == interfaceVTableSize, "");
+        RuntimeAssert(interfaceVTable.size() == static_cast<size_t>(interfaceVTableSize), "");
       }
     }
 
diff --git a/runtime/src/main/cpp/Porting.cpp b/runtime/src/main/cpp/Porting.cpp
index eae63ad353c..953c16cecdd 100644
--- a/runtime/src/main/cpp/Porting.cpp
+++ b/runtime/src/main/cpp/Porting.cpp
@@ -154,7 +154,7 @@ void consolePrintf(const char* format, ...) {
   va_start(args, format);
   int rv = vsnprintf_impl(buffer, sizeof(buffer), format, args);
   if (rv < 0) return; // TODO: this may be too much exotic, but should i try to print itoa(error) and terminate?
-  if (rv >= sizeof(buffer)) rv = sizeof(buffer) - 1;  // TODO: Consider realloc or report truncating.
+  if (static_cast<size_t>(rv) >= sizeof(buffer)) rv = sizeof(buffer) - 1;  // TODO: Consider realloc or report truncating.
   va_end(args);
   consoleWriteUtf8(buffer, rv);
 }
@@ -166,7 +166,7 @@ void consoleErrorf(const char* format, ...) {
   va_start(args, format);
   int rv = vsnprintf_impl(buffer, sizeof(buffer), format, args);
   if (rv < 0) return; // TODO: this may be too much exotic, but should i try to print itoa(error) and terminate?
-  if (rv >= sizeof(buffer)) rv = sizeof(buffer) - 1;  // TODO: Consider realloc or report truncating.
+  if (static_cast<size_t>(rv) >= sizeof(buffer)) rv = sizeof(buffer) - 1;  // TODO: Consider realloc or report truncating.
   va_end(args);
   consoleErrorUtf8(buffer, rv);
 }
@@ -451,7 +451,7 @@ extern "C" {
                 100000007UL,
                 1000000007UL
         };
-        int table_length = sizeof(primes)/sizeof(unsigned long);
+        size_t table_length = sizeof(primes)/sizeof(unsigned long);
 
         if (n > primes[table_length - 1]) konan::abort();
 
@@ -490,7 +490,7 @@ extern "C" {
 #ifdef KONAN_WASM
     // Some string.h functions.
     void *memcpy(void *dst, const void *src, size_t n) {
-        for (long i = 0; i != n; ++i)
+        for (size_t i = 0; i != n; ++i)
             *((char*)dst + i) = *((char*)src + i);
         return dst;
     }
@@ -507,7 +507,7 @@ extern "C" {
     }
 
     int memcmp(const void *s1, const void *s2, size_t n) {
-        for (long i = 0; i != n; ++i) {
+        for (size_t i = 0; i != n; ++i) {
             if (*((char*)s1 + i) != *((char*)s2 + i)) {
                 return *((char*)s1 + i) - *((char*)s2 + i);
             }
@@ -516,7 +516,7 @@ extern "C" {
     }
 
     void *memset(void *b, int c, size_t len) {
-        for (long i = 0; i != len; ++i) {
+        for (size_t i = 0; i != len; ++i) {
             *((char*)b + i) = c;
         }
         return b;
@@ -529,7 +529,7 @@ extern "C" {
     }
 
     size_t strnlen(const char *s, size_t maxlen) {
-        for (long i = 0; i<=maxlen; ++i) {
+        for (size_t i = 0; i<=maxlen; ++i) {
             if (s[i] == 0) return i;
         }
         return maxlen;
diff --git a/runtime/src/main/cpp/Regex.cpp b/runtime/src/main/cpp/Regex.cpp
index 94a7858f2d9..b8371d7ed0a 100644
--- a/runtime/src/main/cpp/Regex.cpp
+++ b/runtime/src/main/cpp/Regex.cpp
@@ -607,7 +607,7 @@ KInt Kotlin_text_regex_decomposeString(ArrayHeader* inputCodePoints, KInt inputL
 
 KInt Kotlin_text_regex_decomposeCodePoint(KInt codePoint, ArrayHeader* outputCodePoints, KInt fromIndex) {
   RuntimeAssert(outputCodePoints->type_info() == theIntArrayTypeInfo, "Must be an Int array");
-  RuntimeAssert(fromIndex >= 0 && fromIndex < outputCodePoints->count_, "Start index must be >= 0 and < array size");
+  RuntimeAssert(fromIndex >= 0 && static_cast<uint32_t>(fromIndex) < outputCodePoints->count_, "Start index must be >= 0 and < array size");
   KInt* rawResult = IntArrayAddressOfElementAt(outputCodePoints, fromIndex);
   const Decomposition* decomposition = getDecomposition(codePoint);
   if (decomposition == nullptr) {
diff --git a/runtime/src/main/cpp/Worker.cpp b/runtime/src/main/cpp/Worker.cpp
index b9f58b9b199..830c490ca2a 100644
--- a/runtime/src/main/cpp/Worker.cpp
+++ b/runtime/src/main/cpp/Worker.cpp
@@ -93,7 +93,7 @@ struct Job {
 
     struct {
       KNativePtr operation;
-      KLong whenExecute;
+      uint64_t whenExecute;
     } executeAfter;
   };
 };
@@ -339,6 +339,8 @@ class State {
     Worker* worker = nullptr;
     Locker locker(&lock_);
 
+    RuntimeAssert(afterMicroseconds >= 0, "afterMicroseconds cannot be negative");
+
     auto it = workers_.find(id);
     if (it == workers_.end()) {
       return false;
diff --git a/runtime/src/main/cpp/dlmalloc/malloc.cpp b/runtime/src/main/cpp/dlmalloc/malloc.cpp
index 35f4f3cce66..4cccd167fa7 100644
--- a/runtime/src/main/cpp/dlmalloc/malloc.cpp
+++ b/runtime/src/main/cpp/dlmalloc/malloc.cpp
@@ -1,3 +1,5 @@
+// Uses GNU extension on null pointer arithmetic.
+#pragma clang diagnostic ignored "-Wnull-pointer-arithmetic"
 /*
   This is a version (aka dlmalloc) of malloc/free/realloc written by
   Doug Lea and released to the public domain, as explained at
diff --git a/runtime/src/objc/cpp/ObjCExportCollections.mm b/runtime/src/objc/cpp/ObjCExportCollections.mm
index 50f400f1322..6e01c23eab4 100644
--- a/runtime/src/objc/cpp/ObjCExportCollections.mm
+++ b/runtime/src/objc/cpp/ObjCExportCollections.mm
@@ -69,7 +69,7 @@ void Kotlin_MutableList_setObject(KRef list, KInt index, KRef obj);
 } // extern "C"
 
 static inline KInt objCCapacityToKotlin(NSUInteger capacity) {
-  KInt max = std::numeric_limits<KInt>::max();
+  NSUInteger max = std::numeric_limits<KInt>::max();
   return capacity > max ? max : capacity;
 }