diff --git a/core/deserialization/src/org/jetbrains/kotlin/serialization/deserialization/NotFoundClasses.kt b/core/deserialization/src/org/jetbrains/kotlin/serialization/deserialization/NotFoundClasses.kt
index 27a633626ed..08596d0863b 100644
--- a/core/deserialization/src/org/jetbrains/kotlin/serialization/deserialization/NotFoundClasses.kt
+++ b/core/deserialization/src/org/jetbrains/kotlin/serialization/deserialization/NotFoundClasses.kt
@@ -54,7 +54,7 @@ class NotFoundClasses(private val storageManager: StorageManager, private val mo
     private val typeAliases = storageManager.createMemoizedFunction<ClassRequest, TypeAliasDescriptor> { request ->
         computeClassifier(request, {
             owner, name, isInner, numberOfTypeParametersCount ->
-            MockTypeAliasDescriptor(storageManager, owner, name, numberOfTypeParametersCount)
+            MockTypeAliasDescriptor(storageManager, owner, name, isInner, numberOfTypeParametersCount)
         })
     }
 
@@ -115,6 +115,7 @@ class NotFoundClasses(private val storageManager: StorageManager, private val mo
             storageManager: StorageManager,
             containingDeclaration: DeclarationDescriptor,
             name: Name,
+            private val isInner: Boolean,
             numberOfDeclaredTypeParameters: Int
     ) : AbstractTypeAliasDescriptor(containingDeclaration, Annotations.EMPTY, name, SourceElement.NO_SOURCE, Visibilities.PUBLIC) {
         init {
@@ -136,6 +137,8 @@ class NotFoundClasses(private val storageManager: StorageManager, private val mo
         override val classDescriptor: ClassDescriptor?
             get() = expandedType.constructor.declarationDescriptor as? ClassDescriptor
 
+        override fun isInner(): Boolean = isInner
+
         override fun substitute(substitutor: TypeSubstitutor) = this
 
         override fun toString() = "MockTypeAliasDescriptor[$fqNameUnsafe]"