diff --git a/tests/baselines/reference/fillInMissingTypeArgsOnJSConstructCalls.errors.txt b/tests/baselines/reference/fillInMissingTypeArgsOnJSConstructCalls.errors.txt
new file mode 100644
index 00000000000..966e3e35613
--- /dev/null
+++ b/tests/baselines/reference/fillInMissingTypeArgsOnJSConstructCalls.errors.txt
@@ -0,0 +1,48 @@
+tests/cases/compiler/BaseB.js(2,24): error TS8004: 'type parameter declarations' can only be used in a .ts file.
+tests/cases/compiler/BaseB.js(2,25): error TS1005: ',' expected.
+tests/cases/compiler/BaseB.js(3,14): error TS2304: Cannot find name 'Class'.
+tests/cases/compiler/BaseB.js(3,14): error TS8010: 'types' can only be used in a .ts file.
+tests/cases/compiler/BaseB.js(4,25): error TS2304: Cannot find name 'Class'.
+tests/cases/compiler/BaseB.js(4,25): error TS8010: 'types' can only be used in a .ts file.
+tests/cases/compiler/SubB.js(3,41): error TS8011: 'type arguments' can only be used in a .ts file.
+
+
+==== tests/cases/compiler/BaseA.js (0 errors) ====
+    // regression test for #18254
+    export default class BaseA {
+    }
+==== tests/cases/compiler/SubA.js (0 errors) ====
+    import BaseA from './BaseA';
+    export default class SubA extends BaseA {
+    }
+==== tests/cases/compiler/BaseB.js (6 errors) ====
+    import BaseA from './BaseA';
+    export default class B<T: BaseA> {
+                           ~~~~~~~~
+!!! error TS8004: 'type parameter declarations' can only be used in a .ts file.
+                            ~
+!!! error TS1005: ',' expected.
+        _AClass: Class<T>;
+                 ~~~~~
+!!! error TS2304: Cannot find name 'Class'.
+                 ~~~~~~~~
+!!! error TS8010: 'types' can only be used in a .ts file.
+        constructor(AClass: Class<T>) {
+                            ~~~~~
+!!! error TS2304: Cannot find name 'Class'.
+                            ~~~~~~~~
+!!! error TS8010: 'types' can only be used in a .ts file.
+            this._AClass = AClass;
+        }
+    }
+==== tests/cases/compiler/SubB.js (1 errors) ====
+    import SubA from './SubA';
+    import BaseB from './BaseB';
+    export default class SubB extends BaseB<SubA> {
+                                            ~~~~
+!!! error TS8011: 'type arguments' can only be used in a .ts file.
+        constructor() {
+            super(SubA);
+        }
+    }
+    
\ No newline at end of file
diff --git a/tests/cases/compiler/fillInMissingTypeArgsOnJSConstructCalls.ts b/tests/cases/compiler/fillInMissingTypeArgsOnJSConstructCalls.ts
new file mode 100644
index 00000000000..8ef0f903189
--- /dev/null
+++ b/tests/cases/compiler/fillInMissingTypeArgsOnJSConstructCalls.ts
@@ -0,0 +1,27 @@
+// @allowJs: true
+// @checkJs: true
+// @noEmit: true
+// regression test for #18254
+// @Filename: BaseA.js
+export default class BaseA {
+}
+// @Filename: SubA.js
+import BaseA from './BaseA';
+export default class SubA extends BaseA {
+}
+// @Filename: BaseB.js
+import BaseA from './BaseA';
+export default class B<T: BaseA> {
+    _AClass: Class<T>;
+    constructor(AClass: Class<T>) {
+        this._AClass = AClass;
+    }
+}
+// @Filename: SubB.js
+import SubA from './SubA';
+import BaseB from './BaseB';
+export default class SubB extends BaseB<SubA> {
+    constructor() {
+        super(SubA);
+    }
+}