diff --git a/tests/scripts/generate_bignum_tests.py b/tests/scripts/generate_bignum_tests.py
index a2a9d06..aa7e131 100755
--- a/tests/scripts/generate_bignum_tests.py
+++ b/tests/scripts/generate_bignum_tests.py
@@ -122,7 +122,7 @@
         This may be calculated during initialization and stored as `_result`,
         or calculated when the method is called.
         """
-        pass
+        raise NotImplementedError
 
     @staticmethod
     def value_description(val) -> str: