diff --git a/compiler/backend/src/org/jetbrains/kotlin/codegen/ClassFileFactory.java b/compiler/backend/src/org/jetbrains/kotlin/codegen/ClassFileFactory.java
index 2b80cdc01a3..21f90a8c50a 100644
--- a/compiler/backend/src/org/jetbrains/kotlin/codegen/ClassFileFactory.java
+++ b/compiler/backend/src/org/jetbrains/kotlin/codegen/ClassFileFactory.java
@@ -123,7 +123,7 @@ public class ClassFileFactory implements OutputFileCollection {
         generators.put(outputFilePath, new OutAndSourceFileList(CollectionsKt.toList(sourceFiles)) {
             @Override
             public byte[] asBytes(ClassBuilderFactory factory) {
-                return ModuleMappingKt.serializeToByteArray(moduleProto, state.getMetadataVersion().toArray());
+                return ModuleMappingKt.serializeToByteArray(moduleProto, state.getMetadataVersion(), 0);
             }
 
             @Override
diff --git a/compiler/cli/src/org/jetbrains/kotlin/cli/metadata/MetadataSerializer.kt b/compiler/cli/src/org/jetbrains/kotlin/cli/metadata/MetadataSerializer.kt
index e8cf9e18d4f..0d3eb1dbe3a 100644
--- a/compiler/cli/src/org/jetbrains/kotlin/cli/metadata/MetadataSerializer.kt
+++ b/compiler/cli/src/org/jetbrains/kotlin/cli/metadata/MetadataSerializer.kt
@@ -135,7 +135,7 @@ open class MetadataSerializer(
             for (table in packageTable.values) {
                 table.addTo(this)
             }
-        }.build().serializeToByteArray(JvmMetadataVersion.INSTANCE.toArray()) // TODO: use another version here, not JVM
+        }.build().serializeToByteArray(JvmMetadataVersion.INSTANCE, 0) // TODO: use another version here, not JVM
         // TODO: also, use CommonConfigurationKeys.METADATA_VERSION if needed
 
         kotlinModuleFile.parentFile.mkdirs()
diff --git a/core/metadata.jvm/src/org/jetbrains/kotlin/metadata/jvm/deserialization/ModuleMapping.kt b/core/metadata.jvm/src/org/jetbrains/kotlin/metadata/jvm/deserialization/ModuleMapping.kt
index cfd63cac1a9..10cead42bd5 100644
--- a/core/metadata.jvm/src/org/jetbrains/kotlin/metadata/jvm/deserialization/ModuleMapping.kt
+++ b/core/metadata.jvm/src/org/jetbrains/kotlin/metadata/jvm/deserialization/ModuleMapping.kt
@@ -5,7 +5,9 @@
 
 package org.jetbrains.kotlin.metadata.jvm.deserialization
 
+import org.jetbrains.kotlin.metadata.deserialization.BinaryVersion
 import org.jetbrains.kotlin.metadata.deserialization.NameResolverImpl
+import org.jetbrains.kotlin.metadata.deserialization.isKotlin1Dot4OrLater
 import org.jetbrains.kotlin.metadata.jvm.JvmModuleProtoBuf
 import java.io.*
 
@@ -54,6 +56,11 @@ class ModuleMapping private constructor(
                 return EMPTY
             }
 
+            // Since Kotlin 1.4, we write integer flags between the version and the proto
+            if (isKotlin1Dot4OrLater(version)) {
+                stream.readInt()
+            }
+
             val moduleProto = JvmModuleProtoBuf.Module.parseFrom(stream) ?: return EMPTY
             val result = linkedMapOf<String, PackageParts>()
 
@@ -207,13 +214,17 @@ class PackageParts(val packageFqName: String) {
         (parts + metadataParts).toString()
 }
 
-fun JvmModuleProtoBuf.Module.serializeToByteArray(versionArray: IntArray): ByteArray {
+fun JvmModuleProtoBuf.Module.serializeToByteArray(version: BinaryVersion, flags: Int): ByteArray {
     val moduleMapping = ByteArrayOutputStream(4096)
     val out = DataOutputStream(moduleMapping)
+    val versionArray = version.toArray()
     out.writeInt(versionArray.size)
     for (number in versionArray) {
         out.writeInt(number)
     }
+    if (isKotlin1Dot4OrLater(version)) {
+        out.writeInt(flags)
+    }
     writeTo(out)
     out.flush()
     return moduleMapping.toByteArray()
diff --git a/core/metadata/src/org/jetbrains/kotlin/metadata/deserialization/versionSpecificBehavior.kt b/core/metadata/src/org/jetbrains/kotlin/metadata/deserialization/versionSpecificBehavior.kt
index fd0b9862185..6188bf70615 100644
--- a/core/metadata/src/org/jetbrains/kotlin/metadata/deserialization/versionSpecificBehavior.kt
+++ b/core/metadata/src/org/jetbrains/kotlin/metadata/deserialization/versionSpecificBehavior.kt
@@ -19,7 +19,7 @@ package org.jetbrains.kotlin.metadata.deserialization
 fun isVersionRequirementTableWrittenCorrectly(version: BinaryVersion): Boolean =
     isKotlin1Dot4OrLater(version)
 
-private fun isKotlin1Dot4OrLater(version: BinaryVersion): Boolean {
+fun isKotlin1Dot4OrLater(version: BinaryVersion): Boolean {
     // All metadata versions (JVM, JS, common) will be advanced to 1.4.0 in Kotlin 1.4
     return version.major == 1 && version.minor >= 4
 }
diff --git a/libraries/kotlinx-metadata/jvm/src/kotlinx/metadata/jvm/KotlinModuleMetadata.kt b/libraries/kotlinx-metadata/jvm/src/kotlinx/metadata/jvm/KotlinModuleMetadata.kt
index 7def2c2fd06..6995912e708 100644
--- a/libraries/kotlinx-metadata/jvm/src/kotlinx/metadata/jvm/KotlinModuleMetadata.kt
+++ b/libraries/kotlinx-metadata/jvm/src/kotlinx/metadata/jvm/KotlinModuleMetadata.kt
@@ -8,6 +8,7 @@ package kotlinx.metadata.jvm
 import kotlinx.metadata.InconsistentKotlinMetadataException
 import kotlinx.metadata.KmAnnotation
 import org.jetbrains.kotlin.metadata.jvm.JvmModuleProtoBuf
+import org.jetbrains.kotlin.metadata.jvm.deserialization.JvmMetadataVersion
 import org.jetbrains.kotlin.metadata.jvm.deserialization.ModuleMapping
 import org.jetbrains.kotlin.metadata.jvm.deserialization.PackageParts
 import org.jetbrains.kotlin.metadata.jvm.deserialization.serializeToByteArray
@@ -62,7 +63,7 @@ class KotlinModuleMetadata(@Suppress("CanBeParameter", "MemberVisibilityCanBePri
          *   [KotlinClassHeader.COMPATIBLE_METADATA_VERSION] by default
          */
         fun write(metadataVersion: IntArray = KotlinClassHeader.COMPATIBLE_METADATA_VERSION): KotlinModuleMetadata =
-            KotlinModuleMetadata(b.build().serializeToByteArray(metadataVersion))
+            KotlinModuleMetadata(b.build().serializeToByteArray(JvmMetadataVersion(*metadataVersion), 0))
     }
 
     /**