diff --git a/ets2panda/checker/types/ets/etsUnionType.cpp b/ets2panda/checker/types/ets/etsUnionType.cpp
index 97b5f76d8bd976d910878cb9f7089e0866f5bf64..b927ff0afe924d258ec4e245a599525f8585d695 100644
--- a/ets2panda/checker/types/ets/etsUnionType.cpp
+++ b/ets2panda/checker/types/ets/etsUnionType.cpp
@@ -426,8 +426,8 @@ bool ETSUnionType::ExtractType(checker::ETSChecker *checker, checker::Type *sour
             rc = true;
             if (!(*it)->IsETSTypeParameter()) {
                 it = unionTypes.erase(it);
+                continue;
             }
-            continue;
         }
 
         if (checker->Relation()->IsSupertypeOf(constituentType, source)) {
diff --git a/ets2panda/test/runtime/ets/unionTypeParamWithConstrainedGenericType_01.ets b/ets2panda/test/runtime/ets/unionTypeParamWithConstrainedGenericType_01.ets
new file mode 100644
index 0000000000000000000000000000000000000000..a71dab09ef27a171bd6d4bc5711a34d0e4d36113
--- /dev/null
+++ b/ets2panda/test/runtime/ets/unionTypeParamWithConstrainedGenericType_01.ets
@@ -0,0 +1,39 @@
+/*
+ * Copyright (c) 2025 Huawei Device Co., Ltd.
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+class A {
+}
+
+class B extends A {
+}
+
+function foo<T extends A>(a: T | string): T | string {
+    if (a instanceof A) {
+      const x: T = a as T;
+      return x;
+    }
+    else {
+      const y: string = a as string;
+      return y;
+    }
+}
+function main(){
+  const a = new A();
+  arktest.assertEQ(foo(a), a)
+  const b = new B();
+  arktest.assertEQ(foo(b), b)
+  arktest.assertEQ(foo(""), "")
+  arktest.assertEQ(foo("123"), "123")
+}
\ No newline at end of file
diff --git a/ets2panda/test/runtime/ets/unionTypeParamWithConstrainedGenericType_02.ets b/ets2panda/test/runtime/ets/unionTypeParamWithConstrainedGenericType_02.ets
new file mode 100644
index 0000000000000000000000000000000000000000..2e6298bed6276f09cbe1fd51f00daa63994efbee
--- /dev/null
+++ b/ets2panda/test/runtime/ets/unionTypeParamWithConstrainedGenericType_02.ets
@@ -0,0 +1,40 @@
+/*
+ * Copyright (c) 2025 Huawei Device Co., Ltd.
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+class A {
+    x: string | undefined
+}
+
+interface I {
+    x: string
+}
+
+function foo<T extends A>(a: T | I): T | I {
+    if (a instanceof A) {
+      const x: T = a as T;
+      return x;
+    }
+    else {
+      const y: I = a as I;
+      return y;
+    }
+}
+
+function main(){
+  const a = new A();
+  arktest.assertEQ(foo(a), a)
+  const i: I = {x: "a"};
+  arktest.assertEQ(foo(i), i)
+}