diff --git a/reasoning_gym/arithmetic/bitwise_arithmetic.py b/reasoning_gym/arithmetic/bitwise_arithmetic.py
index 887c0b4e..5c76b962 100644
--- a/reasoning_gym/arithmetic/bitwise_arithmetic.py
+++ b/reasoning_gym/arithmetic/bitwise_arithmetic.py
@@ -96,8 +96,9 @@ def verify_solution(problem, user_solution):
     """
     try:
         correct_value = eval(problem)
+        # Use base=0 for automatic base detection: 0x->hex, 0b->binary, 0o->octal, no prefix->decimal
         user_value = int(str(user_solution), 0)
-    except Exception as e:
+    except Exception:
         return False
 
     return correct_value == user_value