diff --git a/idea/src/org/jetbrains/kotlin/idea/highlighter/markers/DeclaredHeaderMarker.kt b/idea/src/org/jetbrains/kotlin/idea/highlighter/markers/DeclaredHeaderMarker.kt
index 5b6fdacde08..dfdac955acf 100644
--- a/idea/src/org/jetbrains/kotlin/idea/highlighter/markers/DeclaredHeaderMarker.kt
+++ b/idea/src/org/jetbrains/kotlin/idea/highlighter/markers/DeclaredHeaderMarker.kt
@@ -35,7 +35,7 @@ private fun ModuleDescriptor.declarationOf(descriptor: MemberDescriptor) =
             when (descriptor) {
                 is CallableMemberDescriptor ->
                     descriptor.findNamesakesFromTheSameModule().filter { it.isHeader }.firstOrNull()
-                is ClassDescriptor ->
+                is ClassifierDescriptorWithTypeParameters ->
                     descriptor.findClassifiersFromTheSameModule().filter { it is ClassDescriptor && it.isHeader }.firstOrNull()
                 else ->
                     null
diff --git a/idea/src/org/jetbrains/kotlin/idea/highlighter/markers/ImplementedHeaderMarker.kt b/idea/src/org/jetbrains/kotlin/idea/highlighter/markers/ImplementedHeaderMarker.kt
index 6a4f0b7d615..9e95acd69ff 100644
--- a/idea/src/org/jetbrains/kotlin/idea/highlighter/markers/ImplementedHeaderMarker.kt
+++ b/idea/src/org/jetbrains/kotlin/idea/highlighter/markers/ImplementedHeaderMarker.kt
@@ -34,7 +34,7 @@ private fun ModuleDescriptor.implementationsOf(descriptor: MemberDescriptor) =
         with (HeaderImplDeclarationChecker(this)) {
             when (descriptor) {
                 is CallableMemberDescriptor -> descriptor.findNamesakesFromTheSameModule().filter { it.isImpl }
-                is ClassDescriptor -> descriptor.findClassifiersFromTheSameModule().filter { it is ClassDescriptor && it.isImpl }
+                is ClassDescriptor -> descriptor.findClassifiersFromTheSameModule().filter { it.isImpl }
                 else -> emptyList()
             }
         }