diff --git a/tools/codegen/gen.py b/tools/codegen/gen.py
index af3ebbf674f4..8c22c1fe702c 100644
--- a/tools/codegen/gen.py
+++ b/tools/codegen/gen.py
@@ -471,6 +471,7 @@ def gen_one(f: NativeFunction) -> Optional[str]:
 
         return list(mapMaybe(gen_one, g.functions()))
 
+    @method_with_native_function
     def gen_unstructured(self, f: NativeFunction) -> Optional[str]:
         # for mypy type refinement; would be fixed by TODO on target
         assert self.target is not Target.DECLARATION