diff --git a/compiler/ir/backend.jvm/src/org/jetbrains/kotlin/backend/jvm/descriptors/SharedVariablesManager.kt b/compiler/ir/backend.jvm/src/org/jetbrains/kotlin/backend/jvm/descriptors/SharedVariablesManager.kt
index 8c31b0d00ac..318025a34d6 100644
--- a/compiler/ir/backend.jvm/src/org/jetbrains/kotlin/backend/jvm/descriptors/SharedVariablesManager.kt
+++ b/compiler/ir/backend.jvm/src/org/jetbrains/kotlin/backend/jvm/descriptors/SharedVariablesManager.kt
@@ -93,7 +93,7 @@ class JvmSharedVariablesManager(val builtIns: KotlinBuiltIns) : SharedVariablesM
         fun getSubstitutedRefConstructor(valueType: KotlinType): ClassConstructorDescriptor =
                 genericRefConstructor.substitute(TypeSubstitutor.create(
                         mapOf(constructorTypeParameter.typeConstructor to TypeProjectionImpl(Variance.INVARIANT, valueType))
-                ))
+                ))!!
 
         val genericElementField: PropertyDescriptor =
                 PropertyDescriptorImpl.create(
diff --git a/compiler/ir/backend.jvm/src/org/jetbrains/kotlin/backend/jvm/lower/EnumClassLowering.kt b/compiler/ir/backend.jvm/src/org/jetbrains/kotlin/backend/jvm/lower/EnumClassLowering.kt
index 2c374496ea5..7c31aa8b1b1 100644
--- a/compiler/ir/backend.jvm/src/org/jetbrains/kotlin/backend/jvm/lower/EnumClassLowering.kt
+++ b/compiler/ir/backend.jvm/src/org/jetbrains/kotlin/backend/jvm/lower/EnumClassLowering.kt
@@ -64,7 +64,7 @@ class EnumClassLowering(val context: JvmBackendContext) : ClassLoweringPass {
     private fun createArrayOfExpression(arrayElementType: KotlinType, arrayElements: List<IrExpression>): IrExpression {
         val typeParameter0 = unsubstitutedArrayOfFun.typeParameters[0]
         val typeSubstitutor = TypeSubstitutor.create(mapOf(typeParameter0.typeConstructor to TypeProjectionImpl(arrayElementType)))
-        val substitutedArrayOfFun = unsubstitutedArrayOfFun.substitute(typeSubstitutor)
+        val substitutedArrayOfFun = unsubstitutedArrayOfFun.substitute(typeSubstitutor)!!
 
         val typeArguments = mapOf(typeParameter0 to arrayElementType)
 
@@ -448,7 +448,7 @@ class EnumClassLowering(val context: JvmBackendContext) : ClassLoweringPass {
                 val typeParameterT = unsubstitutedValueOf.typeParameters[0]
                 val enumClassType = irClass.descriptor.defaultType
                 val typeSubstitutor = TypeSubstitutor.create(mapOf(typeParameterT.typeConstructor to TypeProjectionImpl(enumClassType)))
-                val substitutedValueOf = unsubstitutedValueOf.substitute(typeSubstitutor)
+                val substitutedValueOf = unsubstitutedValueOf.substitute(typeSubstitutor)!!
 
                 val irValueOfCall = IrCallImpl(UNDEFINED_OFFSET, UNDEFINED_OFFSET, substitutedValueOf, mapOf(typeParameterT to enumClassType))
                 irValueOfCall.putValueArgument(