diff --git a/core/src/main/java/org/teavm/backend/wasm/generate/gc/classes/WasmGCClassGenerator.java b/core/src/main/java/org/teavm/backend/wasm/generate/gc/classes/WasmGCClassGenerator.java
index 5cf5d6cb7..761095795 100644
--- a/core/src/main/java/org/teavm/backend/wasm/generate/gc/classes/WasmGCClassGenerator.java
+++ b/core/src/main/java/org/teavm/backend/wasm/generate/gc/classes/WasmGCClassGenerator.java
@@ -407,6 +407,7 @@ public class WasmGCClassGenerator implements WasmGCClassInfoProvider, WasmGCInit
                         || expectedFunctionType != function.getType()) {
                     var functionType = typeMapper.getFunctionType(virtualTable.getClassName(), method, true);
                     functionType.getSupertypes().add(expectedFunctionType);
+                    expectedFunctionType.setFinal(false);
                     var wrapperFunction = new WasmFunction(functionType);
                     module.functions.add(wrapperFunction);
                     var call = new WasmCall(function);
diff --git a/core/src/main/java/org/teavm/backend/wasm/model/WasmFunctionType.java b/core/src/main/java/org/teavm/backend/wasm/model/WasmFunctionType.java
index 911fe89c1..7271ea63b 100644
--- a/core/src/main/java/org/teavm/backend/wasm/model/WasmFunctionType.java
+++ b/core/src/main/java/org/teavm/backend/wasm/model/WasmFunctionType.java
@@ -26,6 +26,7 @@ public class WasmFunctionType extends WasmCompositeType {
     private Supplier<List<? extends WasmType>> parameterTypesSupplier;
     private Supplier<WasmType> returnTypeSupplier;
     private Set<WasmFunctionType> supertypes = new LinkedHashSet<>();
+    private boolean isFinal = true;
 
     public WasmFunctionType(String name, WasmType returnType, List<? extends WasmType> parameterTypes) {
         super(name);
@@ -60,6 +61,14 @@ public class WasmFunctionType extends WasmCompositeType {
         return supertypes;
     }
 
+    public boolean isFinal() {
+        return isFinal;
+    }
+
+    public void setFinal(boolean aFinal) {
+        isFinal = aFinal;
+    }
+
     @Override
     public void acceptVisitor(WasmCompositeTypeVisitor visitor) {
         visitor.visit(this);
diff --git a/core/src/main/java/org/teavm/backend/wasm/render/WasmCompositeTypeBinaryRenderer.java b/core/src/main/java/org/teavm/backend/wasm/render/WasmCompositeTypeBinaryRenderer.java
index a3132396b..630c29337 100644
--- a/core/src/main/java/org/teavm/backend/wasm/render/WasmCompositeTypeBinaryRenderer.java
+++ b/core/src/main/java/org/teavm/backend/wasm/render/WasmCompositeTypeBinaryRenderer.java
@@ -57,10 +57,12 @@ public class WasmCompositeTypeBinaryRenderer implements WasmCompositeTypeVisitor
 
     @Override
     public void visit(WasmFunctionType type) {
-        section.writeByte(0x50);
-        section.writeLEB(type.getSupertypes().size());
-        for (var supertype : type.getSupertypes()) {
-            section.writeLEB(module.types.indexOf(supertype));
+        if (!type.isFinal() || !type.getSupertypes().isEmpty()) {
+            section.writeByte(0x50);
+            section.writeLEB(type.getSupertypes().size());
+            for (var supertype : type.getSupertypes()) {
+                section.writeLEB(module.types.indexOf(supertype));
+            }
         }
         section.writeByte(0x60);
         section.writeLEB(type.getParameterTypes().size());