diff --git a/compiler/builtins-serializer/src/org/jetbrains/kotlin/serialization/builtins/BuiltInsSerializerExtension.kt b/compiler/builtins-serializer/src/org/jetbrains/kotlin/serialization/builtins/BuiltInsSerializerExtension.kt
index 338b57e3159..c18ad7465c2 100644
--- a/compiler/builtins-serializer/src/org/jetbrains/kotlin/serialization/builtins/BuiltInsSerializerExtension.kt
+++ b/compiler/builtins-serializer/src/org/jetbrains/kotlin/serialization/builtins/BuiltInsSerializerExtension.kt
@@ -17,17 +17,19 @@
 package org.jetbrains.kotlin.serialization.builtins
 
 import org.jetbrains.kotlin.builtins.BuiltInSerializerProtocol
+import org.jetbrains.kotlin.name.ClassId
+import org.jetbrains.kotlin.name.FqName
 import org.jetbrains.kotlin.serialization.KotlinSerializerExtensionBase
 import org.jetbrains.kotlin.serialization.ProtoBuf
 import org.jetbrains.kotlin.types.KotlinType
 import org.jetbrains.kotlin.types.UnresolvedType
 
 class BuiltInsSerializerExtension : KotlinSerializerExtensionBase(BuiltInSerializerProtocol) {
-    private val shortNameToFullName = mapOf(
-            "IntRange" to "kotlin/ranges/IntRange",
-            "LongRange" to "kotlin/ranges/LongRange",
-            "CharRange" to "kotlin/ranges/CharRange"
-    )
+    private val shortNameToClassId = mapOf(
+            "IntRange" to "kotlin.ranges.IntRange",
+            "LongRange" to "kotlin.ranges.LongRange",
+            "CharRange" to "kotlin.ranges.CharRange"
+    ).mapValues { (_, value) -> ClassId.topLevel(FqName(value)) }
 
     override fun shouldUseTypeTable(): Boolean = true
 
@@ -37,9 +39,9 @@ class BuiltInsSerializerExtension : KotlinSerializerExtensionBase(BuiltInSeriali
             throw UnsupportedOperationException("Error types which are not UnresolvedType instances are not supported here: $unwrapped")
         }
 
-        val fullName = shortNameToFullName[unwrapped.presentableName]
-                       ?: throw UnsupportedOperationException("Unsupported unresolved type: $unwrapped")
+        val classId = shortNameToClassId[unwrapped.presentableName]
+                      ?: throw UnsupportedOperationException("Unsupported unresolved type: $unwrapped")
 
-        builder.className = stringTable.getStringIndex(fullName)
+        builder.className = stringTable.getClassIdIndex(classId)
     }
 }
diff --git a/compiler/serialization/src/org/jetbrains/kotlin/serialization/StringTable.kt b/compiler/serialization/src/org/jetbrains/kotlin/serialization/StringTable.kt
index d96eee8272d..e711050db90 100644
--- a/compiler/serialization/src/org/jetbrains/kotlin/serialization/StringTable.kt
+++ b/compiler/serialization/src/org/jetbrains/kotlin/serialization/StringTable.kt
@@ -16,9 +16,7 @@
 
 package org.jetbrains.kotlin.serialization
 
-import org.jetbrains.kotlin.descriptors.ClassDescriptor
 import org.jetbrains.kotlin.descriptors.ClassifierDescriptorWithTypeParameters
-
 import java.io.OutputStream
 
 interface StringTable {
diff --git a/compiler/serialization/src/org/jetbrains/kotlin/serialization/StringTableImpl.kt b/compiler/serialization/src/org/jetbrains/kotlin/serialization/StringTableImpl.kt
index 864c4760384..427139e58a5 100644
--- a/compiler/serialization/src/org/jetbrains/kotlin/serialization/StringTableImpl.kt
+++ b/compiler/serialization/src/org/jetbrains/kotlin/serialization/StringTableImpl.kt
@@ -16,11 +16,11 @@
 
 package org.jetbrains.kotlin.serialization
 
-import org.jetbrains.kotlin.descriptors.ClassDescriptor
 import org.jetbrains.kotlin.descriptors.ClassifierDescriptorWithTypeParameters
-import org.jetbrains.kotlin.descriptors.PackageFragmentDescriptor
+import org.jetbrains.kotlin.name.ClassId
 import org.jetbrains.kotlin.name.FqName
 import org.jetbrains.kotlin.name.Name
+import org.jetbrains.kotlin.resolve.descriptorUtil.classId
 import org.jetbrains.kotlin.serialization.ProtoBuf.QualifiedNameTable.QualifiedName
 import org.jetbrains.kotlin.types.ErrorUtils
 import org.jetbrains.kotlin.utils.Interner
@@ -58,24 +58,19 @@ open class StringTableImpl : StringTable {
             throw IllegalStateException("Cannot get FQ name of error class: $descriptor")
         }
 
+        val classId = descriptor.classId ?: return getFqNameIndexOfLocalAnonymousClass(descriptor)
+        return getClassIdIndex(classId)
+    }
+
+    fun getClassIdIndex(classId: ClassId): Int {
         val builder = QualifiedName.newBuilder()
         builder.kind = QualifiedName.Kind.CLASS
 
-        val containingDeclaration = descriptor.containingDeclaration
-        when (containingDeclaration) {
-            is PackageFragmentDescriptor -> {
-                val packageFqName = containingDeclaration.fqName
-                if (!packageFqName.isRoot) {
-                    builder.parentQualifiedName = getPackageFqNameIndex(packageFqName)
-                }
-            }
-            is ClassDescriptor -> {
-                builder.parentQualifiedName = getFqNameIndex(containingDeclaration)
-            }
-            else -> return getFqNameIndexOfLocalAnonymousClass(descriptor)
-        }
+        builder.parentQualifiedName =
+                classId.outerClassId?.let(this::getClassIdIndex)
+                ?: getPackageFqNameIndex(classId.packageFqName)
 
-        builder.shortName = getStringIndex(descriptor.name.asString())
+        builder.shortName = getStringIndex(classId.shortClassName.asString())
 
         return qualifiedNames.intern(FqNameProto(builder))
     }