diff --git a/compiler/frontend/src/org/jetbrains/kotlin/resolve/lazy/descriptors/LazyClassMemberScope.kt b/compiler/frontend/src/org/jetbrains/kotlin/resolve/lazy/descriptors/LazyClassMemberScope.kt
index 532790cf0ed..e642d2d157b 100644
--- a/compiler/frontend/src/org/jetbrains/kotlin/resolve/lazy/descriptors/LazyClassMemberScope.kt
+++ b/compiler/frontend/src/org/jetbrains/kotlin/resolve/lazy/descriptors/LazyClassMemberScope.kt
@@ -67,7 +67,7 @@ open class LazyClassMemberScope(
             )
         )
         result.addAll(computeExtraDescriptors(NoLookupLocation.FOR_ALREADY_TRACKED))
-        result
+        result.toList()
     }
 
     override fun getContributedDescriptors(