diff --git a/tests/cpydiff/core_arguments.py b/tests/cpydiff/core_function_argcount.py
similarity index 90%
rename from tests/cpydiff/core_arguments.py
rename to tests/cpydiff/core_function_argcount.py
index 4734a80627..5f3dca4dcd 100644
--- a/tests/cpydiff/core_arguments.py
+++ b/tests/cpydiff/core_function_argcount.py
@@ -1,5 +1,5 @@
 """
-categories: Core
+categories: Core,Functions
 description: Error messages for methods may display unexpected argument counts
 cause: MicroPython counts "self" as an argument.
 workaround: Interpret error messages with the information above in mind.