diff --git a/chatarena/environments/umshini/symmetric_content_moderation.py b/chatarena/environments/umshini/symmetric_content_moderation.py
index 1b53187..1eb8c0f 100644
--- a/chatarena/environments/umshini/symmetric_content_moderation.py
+++ b/chatarena/environments/umshini/symmetric_content_moderation.py
@@ -71,6 +71,7 @@ def get_rewards(self) -> tuple[dict[str, float], str, str]:
             return scores, "", ""
 
         violation = False
+        explanation = None
         if self.disable_judging:
             violation = True if random.randint(0, 1) else False
         else: