diff --git a/cppwg/input/module_info.py b/cppwg/input/module_info.py
index 03bc3eb..d658bb0 100644
--- a/cppwg/input/module_info.py
+++ b/cppwg/input/module_info.py
@@ -80,7 +80,7 @@ def is_decl_in_source_path(self, decl: "declaration_t") -> bool:  # noqa: F821
     def sort_classes(self) -> None:
         """Sort the class info collection in inheritance order."""
 
-        def compare(class_info_0: "ClassInfo", class_info_1: "ClassInfo"):
+        def compare(class_info_0: "ClassInfo", class_info_1: "ClassInfo"):  # noqa: F821
             # Sort classes with no declarations to the bottom
             if class_info_0.decls == class_info_1.decls:
                 return 0