diff --git a/.idea/libraries/kotlin_runtime.xml b/.idea/libraries/kotlin_runtime.xml
index 217f24d439d..cb98de382af 100644
--- a/.idea/libraries/kotlin_runtime.xml
+++ b/.idea/libraries/kotlin_runtime.xml
@@ -7,8 +7,6 @@
     <JAVADOC />
     <SOURCES>
       <root url="file://$PROJECT_DIR$/libraries/stdlib/src" />
-      <root url="file://$PROJECT_DIR$/core/builtins/src" />
-      <root url="file://$PROJECT_DIR$/core/runtime.jvm/src" />
     </SOURCES>
   </library>
 </component>
\ No newline at end of file
diff --git a/core/builtins/builtins.iml b/core/builtins/builtins.iml
index ef582b1af94..c90834f2d60 100644
--- a/core/builtins/builtins.iml
+++ b/core/builtins/builtins.iml
@@ -2,9 +2,10 @@
 <module type="JAVA_MODULE" version="4">
   <component name="NewModuleRootManager" inherit-compiler-output="true">
     <exclude-output />
-    <content url="file://$MODULE_DIR$" />
+    <content url="file://$MODULE_DIR$">
+      <sourceFolder url="file://$MODULE_DIR$/src" isTestSource="false" />
+    </content>
     <orderEntry type="inheritedJdk" />
     <orderEntry type="sourceFolder" forTests="false" />
   </component>
-</module>
-
+</module>
\ No newline at end of file
diff --git a/core/reflection.jvm/reflection.jvm.iml b/core/reflection.jvm/reflection.jvm.iml
index c27ceec3095..401fe141a0d 100644
--- a/core/reflection.jvm/reflection.jvm.iml
+++ b/core/reflection.jvm/reflection.jvm.iml
@@ -8,6 +8,7 @@
     <orderEntry type="inheritedJdk" />
     <orderEntry type="sourceFolder" forTests="false" />
     <orderEntry type="module" module-name="builtins" />
+    <orderEntry type="module" module-name="runtime.jvm" />
     <orderEntry type="module" module-name="descriptors.runtime" />
     <orderEntry type="library" name="kotlin-runtime" level="project" />
   </component>
diff --git a/core/runtime.jvm/runtime.jvm.iml b/core/runtime.jvm/runtime.jvm.iml
index b5df517c6fb..7ce21791fb6 100644
--- a/core/runtime.jvm/runtime.jvm.iml
+++ b/core/runtime.jvm/runtime.jvm.iml
@@ -2,7 +2,9 @@
 <module type="JAVA_MODULE" version="4">
   <component name="NewModuleRootManager" inherit-compiler-output="true">
     <exclude-output />
-    <content url="file://$MODULE_DIR$" />
+    <content url="file://$MODULE_DIR$">
+      <sourceFolder url="file://$MODULE_DIR$/src" isTestSource="false" />
+    </content>
     <orderEntry type="inheritedJdk" />
     <orderEntry type="sourceFolder" forTests="false" />
     <orderEntry type="module" module-name="builtins" />
diff --git a/core/runtime.jvm/src/kotlin/jvm/internal/Lambda.kt b/core/runtime.jvm/src/kotlin/jvm/internal/Lambda.kt
index 59e857a5b10..a8b68232083 100644
--- a/core/runtime.jvm/src/kotlin/jvm/internal/Lambda.kt
+++ b/core/runtime.jvm/src/kotlin/jvm/internal/Lambda.kt
@@ -19,5 +19,6 @@ package kotlin.jvm.internal
 public abstract class Lambda(private val arity: Int) : FunctionImpl() {
     override fun getArity() = arity
 
+    @suppress("PLATFORM_CLASS_MAPPED_TO_KOTLIN")
     override fun toString() = "${(this as Object).getClass().getGenericInterfaces()[0]}"
 }
diff --git a/core/runtime.jvm/src/kotlin/jvm/internal/PrimitiveSpreadBuilders.kt b/core/runtime.jvm/src/kotlin/jvm/internal/PrimitiveSpreadBuilders.kt
index bca205a0877..0646197b3ac 100644
--- a/core/runtime.jvm/src/kotlin/jvm/internal/PrimitiveSpreadBuilders.kt
+++ b/core/runtime.jvm/src/kotlin/jvm/internal/PrimitiveSpreadBuilders.kt
@@ -20,6 +20,8 @@ private abstract class PrimitiveSpreadBuilder<T : Any>(private val size: Int) {
     abstract protected fun T.getSize(): Int
 
     protected var position: Int = 0
+
+    @suppress("CAST_NEVER_SUCCEEDS")
     private val spreads: Array<T?> = arrayOfNulls<Any>(size) as Array<T?>
 
     public fun addSpread(spreadArgument: T) {
@@ -41,17 +43,17 @@ private abstract class PrimitiveSpreadBuilder<T : Any>(private val size: Int) {
             val spreadArgument = spreads[i]
             if (spreadArgument != null) {
                 if (copyValuesFrom < i) {
-                    System.arraycopy(values, copyValuesFrom, result, dstIndex, i-copyValuesFrom)
+                    System.arraycopy(values, copyValuesFrom, result, dstIndex, i - copyValuesFrom)
                     dstIndex += i - copyValuesFrom
                 }
                 val spreadSize = spreadArgument.getSize()
                 System.arraycopy(spreadArgument, 0, result, dstIndex, spreadSize)
                 dstIndex += spreadSize
-                copyValuesFrom = i+1
+                copyValuesFrom = i + 1
             }
         }
         if (copyValuesFrom < size) {
-            System.arraycopy(values, copyValuesFrom, result, dstIndex, size-copyValuesFrom)
+            System.arraycopy(values, copyValuesFrom, result, dstIndex, size - copyValuesFrom)
         }
 
         return result