diff --git a/core/deserialization/src/org/jetbrains/kotlin/serialization/deserialization/builtins/BuiltInsPackageFragmentImpl.kt b/core/deserialization/src/org/jetbrains/kotlin/serialization/deserialization/builtins/BuiltInsPackageFragmentImpl.kt
index 021747c0dbe..20157c2821e 100644
--- a/core/deserialization/src/org/jetbrains/kotlin/serialization/deserialization/builtins/BuiltInsPackageFragmentImpl.kt
+++ b/core/deserialization/src/org/jetbrains/kotlin/serialization/deserialization/builtins/BuiltInsPackageFragmentImpl.kt
@@ -9,7 +9,6 @@ import org.jetbrains.kotlin.builtins.BuiltInsPackageFragment
 import org.jetbrains.kotlin.descriptors.ModuleDescriptor
 import org.jetbrains.kotlin.metadata.ProtoBuf
 import org.jetbrains.kotlin.metadata.builtins.BuiltInsBinaryVersion
-import org.jetbrains.kotlin.metadata.builtins.readBuiltinsPackageFragment
 import org.jetbrains.kotlin.name.FqName
 import org.jetbrains.kotlin.resolve.descriptorUtil.module
 import org.jetbrains.kotlin.serialization.deserialization.DeserializedPackageFragmentImpl
@@ -34,15 +33,21 @@ class BuiltInsPackageFragmentImpl private constructor(
             inputStream: InputStream,
             isFallback: Boolean
         ): BuiltInsPackageFragmentImpl {
-            val (proto, version) = inputStream.readBuiltinsPackageFragment()
+            lateinit var version: BuiltInsBinaryVersion
 
-            if (proto == null) {
-                // TODO: report a proper diagnostic
-                throw UnsupportedOperationException(
-                    "Kotlin built-in definition format version is not supported: " +
-                            "expected ${BuiltInsBinaryVersion.INSTANCE}, actual $version. " +
-                            "Please update Kotlin"
-                )
+            val proto = inputStream.use { stream ->
+                version = BuiltInsBinaryVersion.readFrom(stream)
+
+                if (!version.isCompatible()) {
+                    // TODO: report a proper diagnostic
+                    throw UnsupportedOperationException(
+                        "Kotlin built-in definition format version is not supported: " +
+                                "expected ${BuiltInsBinaryVersion.INSTANCE}, actual $version. " +
+                                "Please update Kotlin"
+                    )
+                }
+
+                ProtoBuf.PackageFragment.parseFrom(stream, BuiltInSerializerProtocol.extensionRegistry)
             }
 
             return BuiltInsPackageFragmentImpl(fqName, storageManager, module, proto, version, isFallback)
diff --git a/core/metadata/src/org/jetbrains/kotlin/metadata/builtins/readPackageFragment.kt b/core/metadata/src/org/jetbrains/kotlin/metadata/builtins/readPackageFragment.kt
deleted file mode 100644
index 4a43d024fff..00000000000
--- a/core/metadata/src/org/jetbrains/kotlin/metadata/builtins/readPackageFragment.kt
+++ /dev/null
@@ -1,22 +0,0 @@
-/*
- * Copyright 2010-2020 JetBrains s.r.o. and Kotlin Programming Language contributors.
- * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
- */
-
-package org.jetbrains.kotlin.metadata.builtins
-
-import org.jetbrains.kotlin.metadata.ProtoBuf
-import org.jetbrains.kotlin.protobuf.ExtensionRegistryLite
-import java.io.InputStream
-
-fun InputStream.readBuiltinsPackageFragment(): Pair<ProtoBuf.PackageFragment?, BuiltInsBinaryVersion> =
-    use { stream ->
-        val version = BuiltInsBinaryVersion.readFrom(stream)
-        val proto =
-            if (version.isCompatible()) ProtoBuf.PackageFragment.parseFrom(
-                stream,
-                ExtensionRegistryLite.newInstance().apply(BuiltInsProtoBuf::registerAllExtensions)
-            )
-            else null
-        proto to version
-    }
diff --git a/libraries/kotlinx-metadata/jvm/src/kotlinx/metadata/jvm/impl/JvmMetadataExtensions.kt b/libraries/kotlinx-metadata/jvm/src/kotlinx/metadata/jvm/impl/JvmMetadataExtensions.kt
index cbaf9e9aa25..8e63e1f31ae 100644
--- a/libraries/kotlinx-metadata/jvm/src/kotlinx/metadata/jvm/impl/JvmMetadataExtensions.kt
+++ b/libraries/kotlinx-metadata/jvm/src/kotlinx/metadata/jvm/impl/JvmMetadataExtensions.kt
@@ -298,12 +298,7 @@ internal class JvmMetadataExtensions : MetadataExtensions {
     override fun createPackageExtension(): KmPackageExtension = JvmPackageExtension()
 
     override fun createModuleFragmentExtensions(): KmModuleFragmentExtension =
-        object : KmModuleFragmentExtension {
-            override val type: KmExtensionType = KmExtensionType(KmModuleFragmentExtension::class)
-
-            override fun accept(visitor: KmModuleFragmentExtensionVisitor) {
-            }
-        }
+        error("metadata-jvm doesn't have any extensions for module fragment!")
 
     override fun createFunctionExtension(): KmFunctionExtension = JvmFunctionExtension()
 
diff --git a/libraries/kotlinx-metadata/src/kotlinx/metadata/internal/common/KotlinCommonMetadata.kt b/libraries/kotlinx-metadata/src/kotlinx/metadata/internal/common/KotlinCommonMetadata.kt
deleted file mode 100644
index bde301ce7db..00000000000
--- a/libraries/kotlinx-metadata/src/kotlinx/metadata/internal/common/KotlinCommonMetadata.kt
+++ /dev/null
@@ -1,44 +0,0 @@
-/*
- * Copyright 2010-2022 JetBrains s.r.o. and Kotlin Programming Language contributors.
- * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
- */
-
-package kotlinx.metadata.internal.common
-
-import kotlinx.metadata.KmModuleFragment
-import kotlinx.metadata.KmModuleFragmentVisitor
-import kotlinx.metadata.impl.accept
-import org.jetbrains.kotlin.metadata.ProtoBuf
-import org.jetbrains.kotlin.metadata.builtins.readBuiltinsPackageFragment
-import org.jetbrains.kotlin.metadata.deserialization.NameResolverImpl
-import java.io.ByteArrayInputStream
-
-class KotlinCommonMetadata private constructor(private val proto: ProtoBuf.PackageFragment) {
-    fun toKmModuleFragment(): KmModuleFragment =
-        KmModuleFragment().apply(this::accept)
-
-    class Writer : KmModuleFragmentVisitor() {
-        // TODO
-    }
-
-    fun accept(v: KmModuleFragmentVisitor) {
-        val strings = NameResolverImpl(proto.strings, proto.qualifiedNames)
-        if (proto.hasPackage()) {
-            v.visitPackage()?.let { proto.`package`.accept(it, strings) }
-        }
-        for (klass in proto.class_List) {
-            v.visitClass()?.let { klass.accept(it, strings) }
-        }
-        v.visitEnd()
-    }
-
-    companion object {
-        @JvmStatic
-        fun read(bytes: ByteArray): KotlinCommonMetadata? {
-            val (proto, _) = ByteArrayInputStream(bytes).readBuiltinsPackageFragment()
-            if (proto == null) return null
-
-            return KotlinCommonMetadata(proto)
-        }
-    }
-}