diff --git a/compiler/backend/src/org/jetbrains/kotlin/codegen/AsmUtil.java b/compiler/backend/src/org/jetbrains/kotlin/codegen/AsmUtil.java
index 73ced433f33..5160b6ee94b 100644
--- a/compiler/backend/src/org/jetbrains/kotlin/codegen/AsmUtil.java
+++ b/compiler/backend/src/org/jetbrains/kotlin/codegen/AsmUtil.java
@@ -265,6 +265,7 @@ public class AsmUtil {
             return getVisibilityAccessFlagForAnonymous(descriptor);
         }
         if (descriptor.getVisibility() == Visibilities.PUBLIC ||
+            descriptor.getVisibility() == Visibilities.PROTECTED ||
             // TODO: should be package private, but for now Kotlin's reflection can't access members of such classes
             descriptor.getVisibility() == Visibilities.LOCAL ||
             descriptor.getVisibility() == Visibilities.INTERNAL) {
diff --git a/compiler/testData/codegen/box/innerNested/protectedNestedClass.kt b/compiler/testData/codegen/box/innerNested/protectedNestedClass.kt
new file mode 100644
index 00000000000..122cc29a12c
--- /dev/null
+++ b/compiler/testData/codegen/box/innerNested/protectedNestedClass.kt
@@ -0,0 +1,26 @@
+// See KT-9246 IllegalAccessError when trying to access protected nested class from parent class
+// TARGET_BACKEND: JVM
+// FILE: a.kt
+
+package a
+
+abstract class A {
+    protected class C {
+        fun result() = "OK"
+    }
+}
+
+// FILE: b.kt
+
+package b
+
+import a.A
+
+class B : A() {
+    protected val c = A.C()
+    val result: String get() = c.result()
+}
+
+fun box(): String {
+    return B().result
+}
diff --git a/compiler/testData/codegen/box/innerNested/protectedNestedClassFromJava.kt b/compiler/testData/codegen/box/innerNested/protectedNestedClassFromJava.kt
new file mode 100644
index 00000000000..1dbc087f9c9
--- /dev/null
+++ b/compiler/testData/codegen/box/innerNested/protectedNestedClassFromJava.kt
@@ -0,0 +1,34 @@
+// See KT-8269 java.lang.IllegalAccessError on accessing protected inner class declared in Kotlin super class
+// TARGET_BACKEND: JVM
+// FILE: Test.kt
+
+package com.company
+
+import other.JavaClass
+
+open class Test {
+    protected class ProtectedClass
+}
+
+fun box(): String {
+    JavaClass.test()
+    return "OK"
+}
+
+// FILE: other/JavaClass.java
+
+package other;
+
+import com.company.Test;
+
+public class JavaClass {
+    static class JavaTest extends Test {
+        public static boolean foo(Object obj) {
+            return obj instanceof ProtectedClass;
+        }
+    }
+
+    public static void test() {
+        JavaTest.foo(new Object());
+    }
+}
diff --git a/compiler/testData/codegen/box/regressions/kt10143.kt b/compiler/testData/codegen/box/regressions/kt10143.kt
new file mode 100644
index 00000000000..33a0cbbce16
--- /dev/null
+++ b/compiler/testData/codegen/box/regressions/kt10143.kt
@@ -0,0 +1,33 @@
+// FILE: Outer.kt
+
+package another
+open class Outer {
+    protected class Stage(val run: () -> Unit)
+    protected class My(var stage: Stage? = null) {
+        fun initStage(f: () -> Unit): Stage {
+            stage = Stage(f)
+            return stage!!
+        }
+    }
+    protected fun my(init: My.() -> Unit): My {
+        val result = My()
+        result.init()
+        return result
+    }
+}
+
+// FILE: Main.kt
+
+package other
+class Derived : another.Outer() {
+    init {
+        my {
+            initStage { }
+        }
+    }
+}
+
+fun box(): String {
+    Derived()
+    return "OK"
+}
diff --git a/compiler/tests/org/jetbrains/kotlin/codegen/BlackBoxCodegenTestGenerated.java b/compiler/tests/org/jetbrains/kotlin/codegen/BlackBoxCodegenTestGenerated.java
index 773cc2532f3..6a205ae670d 100644
--- a/compiler/tests/org/jetbrains/kotlin/codegen/BlackBoxCodegenTestGenerated.java
+++ b/compiler/tests/org/jetbrains/kotlin/codegen/BlackBoxCodegenTestGenerated.java
@@ -6876,6 +6876,18 @@ public class BlackBoxCodegenTestGenerated extends AbstractBlackBoxCodegenTest {
             String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/box/innerNested/nestedSimple.kt");
             doTest(fileName);
         }
+
+        @TestMetadata("protectedNestedClass.kt")
+        public void testProtectedNestedClass() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/box/innerNested/protectedNestedClass.kt");
+            doTest(fileName);
+        }
+
+        @TestMetadata("protectedNestedClassFromJava.kt")
+        public void testProtectedNestedClassFromJava() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/box/innerNested/protectedNestedClassFromJava.kt");
+            doTest(fileName);
+        }
     }
 
     @TestMetadata("compiler/testData/codegen/box/instructions")
@@ -11875,6 +11887,12 @@ public class BlackBoxCodegenTestGenerated extends AbstractBlackBoxCodegenTest {
             doTest(fileName);
         }
 
+        @TestMetadata("kt10143.kt")
+        public void testKt10143() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/box/regressions/kt10143.kt");
+            doTest(fileName);
+        }
+
         @TestMetadata("kt10934.kt")
         public void testKt10934() throws Exception {
             String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/box/regressions/kt10934.kt");
diff --git a/js/js.tests/test/org/jetbrains/kotlin/js/test/semantics/InnerNestedTestGenerated.java b/js/js.tests/test/org/jetbrains/kotlin/js/test/semantics/InnerNestedTestGenerated.java
index 4df2f74e968..dd9cc2c7670 100644
--- a/js/js.tests/test/org/jetbrains/kotlin/js/test/semantics/InnerNestedTestGenerated.java
+++ b/js/js.tests/test/org/jetbrains/kotlin/js/test/semantics/InnerNestedTestGenerated.java
@@ -43,6 +43,18 @@ public class InnerNestedTestGenerated extends AbstractInnerNestedTest {
         doTest(fileName);
     }
 
+    @TestMetadata("protectedNestedClass.kt")
+    public void ignoredProtectedNestedClass() throws Exception {
+        String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/box/innerNested/protectedNestedClass.kt");
+        doTest(fileName);
+    }
+
+    @TestMetadata("protectedNestedClassFromJava.kt")
+    public void ignoredProtectedNestedClassFromJava() throws Exception {
+        String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/box/innerNested/protectedNestedClassFromJava.kt");
+        doTest(fileName);
+    }
+
     public void testAllFilesPresentInInnerNested() throws Exception {
         KotlinTestUtils.assertAllTestsPresentByMetadata(this.getClass(), new File("compiler/testData/codegen/box/innerNested"), Pattern.compile("^(.+)\\.kt$"), true);
     }