diff --git a/compiler/fir/fir-serialization/src/org/jetbrains/kotlin/fir/serialization/FirElementSerializer.kt b/compiler/fir/fir-serialization/src/org/jetbrains/kotlin/fir/serialization/FirElementSerializer.kt
index 15f1eee1532..3cc1d0d6752 100644
--- a/compiler/fir/fir-serialization/src/org/jetbrains/kotlin/fir/serialization/FirElementSerializer.kt
+++ b/compiler/fir/fir-serialization/src/org/jetbrains/kotlin/fir/serialization/FirElementSerializer.kt
@@ -418,7 +418,8 @@ class FirElementSerializer private constructor(
                 val isFakeOverrideOfAnyFunctionInDataOrValueClass = this@collectDeclarations is FirRegularClass &&
                         (this@collectDeclarations.isData || this@collectDeclarations.isInline) &&
                         dispatchReceiverLookupTag?.classId == StandardClassIds.Any && !declaration.isFinal
-                if (isFakeOverrideOfAnyFunctionInDataOrValueClass ||
+                // Related: https://youtrack.jetbrains.com/issue/KT-20427#focus=Comments-27-8652759.0-0
+                if (isFakeOverrideOfAnyFunctionInDataOrValueClass && !this@collectDeclarations.isExpect ||
                     !declaration.isSubstitutionOrIntersectionOverride &&
                     (declaration.isStatic || declaration is FirConstructor || dispatchReceiverLookupTag == this@collectDeclarations.symbol.toLookupTag())
                 ) {
diff --git a/compiler/fir/providers/src/org/jetbrains/kotlin/fir/scopes/FirKotlinScopeProvider.kt b/compiler/fir/providers/src/org/jetbrains/kotlin/fir/scopes/FirKotlinScopeProvider.kt
index cde3008a22b..fcf84c88eac 100644
--- a/compiler/fir/providers/src/org/jetbrains/kotlin/fir/scopes/FirKotlinScopeProvider.kt
+++ b/compiler/fir/providers/src/org/jetbrains/kotlin/fir/scopes/FirKotlinScopeProvider.kt
@@ -62,6 +62,7 @@ class FirKotlinScopeProvider(
                     FirDelegatedMemberScope(useSiteSession, scopeSession, klass, it, delegateFields)
             }
             val declaredMemberScopeWithPossiblySynthesizedMembers =
+                // Related: https://youtrack.jetbrains.com/issue/KT-20427#focus=Comments-27-8652759.0-0
                 if (klass is FirRegularClass && !klass.isExpect && (klass.isData || klass.isInline)) {
                     // See also KT-58926 (we apply delegation first, and data/value classes after it)
                     FirClassAnySynthesizedMemberScope(useSiteSession, possiblyDelegatedDeclaredMemberScope, klass, scopeSession)
diff --git a/libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/kotlin/org/jetbrains/kotlin/gradle/mpp/MppDiagnosticsIt.kt b/libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/kotlin/org/jetbrains/kotlin/gradle/mpp/MppDiagnosticsIt.kt
index 2906a04574e..859ac60fbd3 100644
--- a/libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/kotlin/org/jetbrains/kotlin/gradle/mpp/MppDiagnosticsIt.kt
+++ b/libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/kotlin/org/jetbrains/kotlin/gradle/mpp/MppDiagnosticsIt.kt
@@ -113,6 +113,13 @@ class MppDiagnosticsIt : KGPBaseTest() {
         }
     }
 
+    @GradleTest
+    fun testKt64121(gradleVersion: GradleVersion) {
+        project("kt64121", gradleVersion) {
+            build("assemble")
+        }
+    }
+
     @GradleTest
     fun testSuppressGradlePluginWarnings(gradleVersion: GradleVersion) {
         project("suppressGradlePluginWarnings", gradleVersion) {
diff --git a/libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/resources/testProject/kt64121/build.gradle.kts b/libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/resources/testProject/kt64121/build.gradle.kts
new file mode 100644
index 00000000000..e50d0039bdb
--- /dev/null
+++ b/libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/resources/testProject/kt64121/build.gradle.kts
@@ -0,0 +1,47 @@
+plugins {
+    kotlin("multiplatform")
+    `maven-publish`
+}
+
+repositories {
+    mavenLocal()
+    maven("../repo")
+    mavenCentral()
+}
+
+group = "com.example.bar"
+version = "1.0"
+
+kotlin {
+    js()
+    linuxX64()
+
+    sourceSets {
+        val commonMain by getting {
+            dependencies {
+                implementation(kotlin("stdlib-common"))
+            }
+        }
+
+        val linuxAndJsMain by creating {
+            dependsOn(commonMain)
+        }
+
+        js().compilations["main"].defaultSourceSet {
+            dependsOn(linuxAndJsMain)
+            dependencies {
+                implementation(kotlin("stdlib-js"))
+            }
+        }
+
+        linuxX64().compilations["main"].defaultSourceSet {
+            dependsOn(linuxAndJsMain)
+        }
+    }
+}
+
+publishing {
+    repositories {
+        maven("../repo")
+    }
+}
diff --git a/libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/resources/testProject/kt64121/settings.gradle.kts b/libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/resources/testProject/kt64121/settings.gradle.kts
new file mode 100644
index 00000000000..2bbb87dde93
--- /dev/null
+++ b/libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/resources/testProject/kt64121/settings.gradle.kts
@@ -0,0 +1 @@
+rootProject.name = "my-lib-bar"
diff --git a/libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/resources/testProject/kt64121/src/commonMain/kotlin/Bar.kt b/libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/resources/testProject/kt64121/src/commonMain/kotlin/Bar.kt
new file mode 100644
index 00000000000..a3b10021d8d
--- /dev/null
+++ b/libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/resources/testProject/kt64121/src/commonMain/kotlin/Bar.kt
@@ -0,0 +1,7 @@
+package com.example.bar
+
+expect value class Bar(val value: String)
+
+expect value class Foo(val value: String) {
+    override fun toString(): String
+}
diff --git a/libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/resources/testProject/kt64121/src/linuxAndJsMain/kotlin/BarLinuxAndJs.kt b/libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/resources/testProject/kt64121/src/linuxAndJsMain/kotlin/BarLinuxAndJs.kt
new file mode 100644
index 00000000000..02b73f1bace
--- /dev/null
+++ b/libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/resources/testProject/kt64121/src/linuxAndJsMain/kotlin/BarLinuxAndJs.kt
@@ -0,0 +1,13 @@
+package com.example.bar
+
+actual value class Bar actual constructor(actual val value: String){
+    override fun toString(): String {
+        return value
+    }
+}
+
+actual value class Foo actual constructor(actual val value: String){
+    actual override fun toString(): String {
+        return value
+    }
+}