diff --git a/dimos/protocol/pubsub/shmpubsub.py b/dimos/protocol/pubsub/shmpubsub.py
index 6539cfefdb..10f8763496 100644
--- a/dimos/protocol/pubsub/shmpubsub.py
+++ b/dimos/protocol/pubsub/shmpubsub.py
@@ -159,7 +159,8 @@ def publish(self, topic: str, message: bytes) -> None:
             raise ValueError(f"Payload too large: {L} > capacity {st.capacity}")
 
         # Mark this payload to suppress its single echo (handles back-to-back publishes)
-        st.suppress_counts[payload_bytes] += 1
+        payload_hash = hashlib.md5(payload_bytes).digest()
+        st.suppress_counts[payload_hash] += 1
 
         # Synchronous local delivery first (zero extra copies)
         for cb in list(st.subs):
@@ -276,12 +277,13 @@ def _fanout_loop(self, topic: str, st: _TopicState) -> None:
                 payload = host[4 : 4 + L].tobytes()
 
                 # Drop exactly the number of local echoes we created
-                cnt = st.suppress_counts.get(payload, 0)
+                payload_hash = hashlib.md5(payload).digest()
+                cnt = st.suppress_counts.get(payload_hash, 0)
                 if cnt > 0:
                     if cnt == 1:
-                        del st.suppress_counts[payload]
+                        del st.suppress_counts[payload_hash]
                     else:
-                        st.suppress_counts[payload] = cnt - 1
+                        st.suppress_counts[payload_hash] = cnt - 1
                     continue  # suppressed
 
             except Exception: