diff --git a/build-common/src/org/jetbrains/kotlin/incremental/IncrementalJsCache.kt b/build-common/src/org/jetbrains/kotlin/incremental/IncrementalJsCache.kt
index 78ee822cb51..f3be27c672a 100644
--- a/build-common/src/org/jetbrains/kotlin/incremental/IncrementalJsCache.kt
+++ b/build-common/src/org/jetbrains/kotlin/incremental/IncrementalJsCache.kt
@@ -182,10 +182,11 @@ fun getProtoData(sourceFile: File, metadata: ByteArray): Map<ClassId, ProtoData>
     }
 
     proto.`package`.apply {
-        val packageFqName = getExtensionOrNull(JsProtoBuf.packageFqName)?.let(nameResolver::getPackageFqName) ?: FqName.ROOT
+        val packageFqName = getExtensionOrNull(JsProtoBuf.packageFqName)?.let(nameResolver::getPackageFqName)?.let(::FqName) ?: FqName.ROOT
         val packagePartClassId = ClassId(packageFqName, Name.identifier(sourceFile.nameWithoutExtension.capitalize() + "Kt"))
         classes[packagePartClassId] = PackagePartProtoData(this, nameResolver, packageFqName)
     }
+
     return classes
 }
 
diff --git a/core/deserialization/src/org/jetbrains/kotlin/serialization/deserialization/NameResolverImpl.kt b/core/deserialization/src/org/jetbrains/kotlin/serialization/deserialization/NameResolverImpl.kt
index a5789e70e50..be941c83994 100644
--- a/core/deserialization/src/org/jetbrains/kotlin/serialization/deserialization/NameResolverImpl.kt
+++ b/core/deserialization/src/org/jetbrains/kotlin/serialization/deserialization/NameResolverImpl.kt
@@ -18,7 +18,6 @@ package org.jetbrains.kotlin.serialization.deserialization
 
 import org.jetbrains.kotlin.metadata.ProtoBuf
 import org.jetbrains.kotlin.metadata.ProtoBuf.QualifiedNameTable.QualifiedName
-import org.jetbrains.kotlin.name.FqName
 import java.util.*
 
 class NameResolverImpl(
@@ -37,10 +36,8 @@ class NameResolverImpl(
     override fun isLocalClassName(index: Int): Boolean =
         traverseIds(index).third
 
-    fun getPackageFqName(index: Int): FqName {
-        val packageNameSegments = traverseIds(index).first
-        return FqName.fromSegments(packageNameSegments)
-    }
+    fun getPackageFqName(index: Int): String =
+        traverseIds(index).first.joinToString(".")
 
     private fun traverseIds(startingIndex: Int): Triple<List<String>, List<String>, Boolean> {
         var index = startingIndex
diff --git a/idea/idea-analysis/src/org/jetbrains/kotlin/idea/decompiler/common/KotlinMetadataDecompiler.kt b/idea/idea-analysis/src/org/jetbrains/kotlin/idea/decompiler/common/KotlinMetadataDecompiler.kt
index 43b0ee1ac10..b30a45644e0 100644
--- a/idea/idea-analysis/src/org/jetbrains/kotlin/idea/decompiler/common/KotlinMetadataDecompiler.kt
+++ b/idea/idea-analysis/src/org/jetbrains/kotlin/idea/decompiler/common/KotlinMetadataDecompiler.kt
@@ -28,6 +28,7 @@ import org.jetbrains.kotlin.idea.decompiler.textBuilder.DecompiledText
 import org.jetbrains.kotlin.idea.decompiler.textBuilder.buildDecompiledText
 import org.jetbrains.kotlin.idea.decompiler.textBuilder.defaultDecompilerRendererOptions
 import org.jetbrains.kotlin.metadata.ProtoBuf
+import org.jetbrains.kotlin.name.FqName
 import org.jetbrains.kotlin.renderer.DescriptorRenderer
 import org.jetbrains.kotlin.resolve.TargetPlatform
 import org.jetbrains.kotlin.serialization.SerializerExtensionProtocol
@@ -120,7 +121,7 @@ sealed class FileWithMetadata {
             serializerProtocol: SerializerExtensionProtocol
     ) : FileWithMetadata() {
         val nameResolver = NameResolverImpl(proto.strings, proto.qualifiedNames)
-        val packageFqName = nameResolver.getPackageFqName(proto.`package`.getExtension(serializerProtocol.packageFqName))
+        val packageFqName = FqName(nameResolver.getPackageFqName(proto.`package`.getExtension(serializerProtocol.packageFqName)))
 
         open val classesToDecompile: List<ProtoBuf.Class> =
                 proto.class_List.filter { proto ->
diff --git a/jps-plugin/jps-tests/test/org/jetbrains/kotlin/jps/incremental/AbstractJsProtoComparisonTest.kt b/jps-plugin/jps-tests/test/org/jetbrains/kotlin/jps/incremental/AbstractJsProtoComparisonTest.kt
index 7e84fe2dc2d..f796c54aa4d 100644
--- a/jps-plugin/jps-tests/test/org/jetbrains/kotlin/jps/incremental/AbstractJsProtoComparisonTest.kt
+++ b/jps-plugin/jps-tests/test/org/jetbrains/kotlin/jps/incremental/AbstractJsProtoComparisonTest.kt
@@ -20,21 +20,12 @@ import org.jetbrains.kotlin.cli.common.arguments.K2JSCompilerArguments
 import org.jetbrains.kotlin.cli.common.arguments.K2JsArgumentConstants
 import org.jetbrains.kotlin.compilerRunner.OutputItemsCollectorImpl
 import org.jetbrains.kotlin.config.Services
-import org.jetbrains.kotlin.incremental.ClassProtoData
-import org.jetbrains.kotlin.incremental.PackagePartProtoData
 import org.jetbrains.kotlin.incremental.ProtoData
+import org.jetbrains.kotlin.incremental.getProtoData
 import org.jetbrains.kotlin.incremental.js.IncrementalResultsConsumer
 import org.jetbrains.kotlin.incremental.js.IncrementalResultsConsumerImpl
 import org.jetbrains.kotlin.incremental.utils.TestMessageCollector
-import org.jetbrains.kotlin.metadata.ProtoBuf
-import org.jetbrains.kotlin.metadata.js.JsProtoBuf
 import org.jetbrains.kotlin.name.ClassId
-import org.jetbrains.kotlin.name.FqName
-import org.jetbrains.kotlin.name.Name
-import org.jetbrains.kotlin.serialization.deserialization.NameResolverImpl
-import org.jetbrains.kotlin.serialization.deserialization.getClassId
-import org.jetbrains.kotlin.serialization.deserialization.getExtensionOrNull
-import org.jetbrains.kotlin.serialization.js.JsSerializerProtocol
 import org.junit.Assert
 import java.io.File
 
@@ -79,21 +70,3 @@ abstract class AbstractJsProtoComparisonTest : AbstractProtoComparisonTest<Proto
 
     override fun ProtoData.toProtoData(): ProtoData? = this
 }
-
-fun getProtoData(sourceFile: File, metadata: ByteArray): Map<ClassId, ProtoData>  {
-    val classes = hashMapOf<ClassId, ProtoData>()
-    val proto = ProtoBuf.PackageFragment.parseFrom(metadata, JsSerializerProtocol.extensionRegistry)
-    val nameResolver = NameResolverImpl(proto.strings, proto.qualifiedNames)
-
-    proto.class_List.forEach {
-        val classId = nameResolver.getClassId(it.fqName)
-        classes[classId] = ClassProtoData(it, nameResolver)
-    }
-
-    proto.`package`.apply {
-        val packageFqName = getExtensionOrNull(JsProtoBuf.packageFqName)?.let(nameResolver::getPackageFqName) ?: FqName.ROOT
-        val packagePartClassId = ClassId(packageFqName, Name.identifier(sourceFile.nameWithoutExtension.capitalize() + "Kt"))
-        classes[packagePartClassId] = PackagePartProtoData(this, nameResolver, packageFqName)
-    }
-    return classes
-}
diff --git a/js/js.serializer/src/org/jetbrains/kotlin/serialization/js/kotlinJavascriptPackageFragmentProvider.kt b/js/js.serializer/src/org/jetbrains/kotlin/serialization/js/kotlinJavascriptPackageFragmentProvider.kt
index 85db7f92bd9..994b486b6ce 100644
--- a/js/js.serializer/src/org/jetbrains/kotlin/serialization/js/kotlinJavascriptPackageFragmentProvider.kt
+++ b/js/js.serializer/src/org/jetbrains/kotlin/serialization/js/kotlinJavascriptPackageFragmentProvider.kt
@@ -89,7 +89,7 @@ private val ProtoBuf.PackageFragment.fqName: FqName?
     get() {
         val nameResolver = NameResolverImpl(strings, qualifiedNames)
         return when {
-            hasPackage() -> nameResolver.getPackageFqName(`package`.getExtension(JsProtoBuf.packageFqName))
+            hasPackage() -> FqName(nameResolver.getPackageFqName(`package`.getExtension(JsProtoBuf.packageFqName)))
             class_Count > 0 -> nameResolver.getClassId(class_OrBuilderList.first().fqName).packageFqName
             else -> null
         }