diff --git a/compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/transformers/irToJs/JsClassGenerator.kt b/compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/transformers/irToJs/JsClassGenerator.kt
index 58dc913e054..843b9838f75 100644
--- a/compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/transformers/irToJs/JsClassGenerator.kt
+++ b/compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/transformers/irToJs/JsClassGenerator.kt
@@ -5,6 +5,7 @@
 
 package org.jetbrains.kotlin.ir.backend.js.transformers.irToJs
 
+import org.jetbrains.kotlin.descriptors.ClassKind
 import org.jetbrains.kotlin.descriptors.DescriptorVisibilities
 import org.jetbrains.kotlin.ir.backend.js.export.isExported
 import org.jetbrains.kotlin.ir.backend.js.utils.*
@@ -142,6 +143,10 @@ class JsClassGenerator(private val irClass: IrClass, val context: JsGenerationCo
         return this.overriddenSymbols.any { it.owner.overridesExternal() }
     }
 
+    private fun IrClass.shouldCopyFrom(): Boolean {
+        return isInterface && !isEffectivelyExternal()
+    }
+
     private fun generateMemberFunction(declaration: IrSimpleFunction): Pair<JsNameRef, JsFunction?> {
         val memberName = context.getNameForMemberFunction(declaration.realOverrideTarget)
         val memberRef = JsNameRef(memberName, classPrototypeRef)
@@ -158,10 +163,10 @@ class JsClassGenerator(private val irClass: IrClass, val context: JsGenerationCo
         // interface II : I
         // II.prototype.foo = I.prototype.foo
         if (!irClass.isInterface) {
-            declaration.realOverrideTarget.let { it ->
+            declaration.realOverrideTarget.let {
                 val implClassDeclaration = it.parent as IrClass
 
-                if (!implClassDeclaration.defaultType.isAny() && !it.isEffectivelyExternal()) {
+                if (implClassDeclaration.shouldCopyFrom()) {
                     val implMethodName = context.getNameForMemberFunction(it)
                     val implClassName = context.getNameForClass(implClassDeclaration)
 
diff --git a/js/js.tests/test/org/jetbrains/kotlin/js/test/es6/semantics/IrBoxJsES6TestGenerated.java b/js/js.tests/test/org/jetbrains/kotlin/js/test/es6/semantics/IrBoxJsES6TestGenerated.java
index 52090674916..ef593b685e6 100644
--- a/js/js.tests/test/org/jetbrains/kotlin/js/test/es6/semantics/IrBoxJsES6TestGenerated.java
+++ b/js/js.tests/test/org/jetbrains/kotlin/js/test/es6/semantics/IrBoxJsES6TestGenerated.java
@@ -3470,6 +3470,11 @@ public class IrBoxJsES6TestGenerated extends AbstractIrBoxJsES6Test {
             runTest("js/js.translator/testData/box/inheritance/baseClassDefinedAfterDerived.kt");
         }
 
+        @TestMetadata("childPrototype.kt")
+        public void testChildPrototype() throws Exception {
+            runTest("js/js.translator/testData/box/inheritance/childPrototype.kt");
+        }
+
         @TestMetadata("complexInitializationOrder.kt")
         public void testComplexInitializationOrder() throws Exception {
             runTest("js/js.translator/testData/box/inheritance/complexInitializationOrder.kt");
diff --git a/js/js.tests/test/org/jetbrains/kotlin/js/test/ir/semantics/IrBoxJsTestGenerated.java b/js/js.tests/test/org/jetbrains/kotlin/js/test/ir/semantics/IrBoxJsTestGenerated.java
index 9bc0e102973..eb89de9f159 100644
--- a/js/js.tests/test/org/jetbrains/kotlin/js/test/ir/semantics/IrBoxJsTestGenerated.java
+++ b/js/js.tests/test/org/jetbrains/kotlin/js/test/ir/semantics/IrBoxJsTestGenerated.java
@@ -3470,6 +3470,11 @@ public class IrBoxJsTestGenerated extends AbstractIrBoxJsTest {
             runTest("js/js.translator/testData/box/inheritance/baseClassDefinedAfterDerived.kt");
         }
 
+        @TestMetadata("childPrototype.kt")
+        public void testChildPrototype() throws Exception {
+            runTest("js/js.translator/testData/box/inheritance/childPrototype.kt");
+        }
+
         @TestMetadata("complexInitializationOrder.kt")
         public void testComplexInitializationOrder() throws Exception {
             runTest("js/js.translator/testData/box/inheritance/complexInitializationOrder.kt");
diff --git a/js/js.tests/test/org/jetbrains/kotlin/js/test/semantics/BoxJsTestGenerated.java b/js/js.tests/test/org/jetbrains/kotlin/js/test/semantics/BoxJsTestGenerated.java
index c85dde4dc75..4e8759e734f 100644
--- a/js/js.tests/test/org/jetbrains/kotlin/js/test/semantics/BoxJsTestGenerated.java
+++ b/js/js.tests/test/org/jetbrains/kotlin/js/test/semantics/BoxJsTestGenerated.java
@@ -3485,6 +3485,11 @@ public class BoxJsTestGenerated extends AbstractBoxJsTest {
             runTest("js/js.translator/testData/box/inheritance/baseClassDefinedAfterDerived.kt");
         }
 
+        @TestMetadata("childPrototype.kt")
+        public void testChildPrototype() throws Exception {
+            runTest("js/js.translator/testData/box/inheritance/childPrototype.kt");
+        }
+
         @TestMetadata("complexInitializationOrder.kt")
         public void testComplexInitializationOrder() throws Exception {
             runTest("js/js.translator/testData/box/inheritance/complexInitializationOrder.kt");
diff --git a/js/js.translator/testData/box/inheritance/childPrototype.kt b/js/js.translator/testData/box/inheritance/childPrototype.kt
new file mode 100644
index 00000000000..60ee1821c8d
--- /dev/null
+++ b/js/js.translator/testData/box/inheritance/childPrototype.kt
@@ -0,0 +1,32 @@
+// EXPECTED_REACHABLE_NODES: 1251
+
+// KT-41227
+
+var result = ""
+
+open class A {
+    @JsName("foo")
+    fun foo() { result += "A" }
+    @JsName("boo")
+    open fun boo() { result += "FAIL" }
+}
+
+class B : A() {
+    override fun boo() { result += "B" }
+    @JsName("bar")
+    fun bar() { result += "C" }
+}
+
+fun box(): String {
+    val b = B()
+    b.boo()
+    b.foo()
+    b.bar()
+    if (result != "BAC") return "FAIL: $result"
+
+    return "OK"
+}
+
+// PROPERTY_WRITE_COUNT: name=foo count=1
+// PROPERTY_WRITE_COUNT: name=boo count=2
+// PROPERTY_WRITE_COUNT: name=bar count=1
\ No newline at end of file