diff --git a/flake.nix b/flake.nix
index afc96639d..927cd21f6 100644
--- a/flake.nix
+++ b/flake.nix
@@ -29,7 +29,7 @@
           ];
           doCheck = false;
           # FIXME: This needs to be manually changed when updating modules.
-          vendorSha256 = "sha256-D0IwlMmCW32T/bfmJjFu3Mlg7pgW4j8IJGZUQ6fnHJQ=";
+          vendorSha256 = "sha256-pNkh5ZJEhC/X/SoqfWcm3w7W1EGOT3m2dzePM/XuA9w=";
           # Fix for 'nix run' trying to execute 'go-waku'.
           meta = { mainProgram = "waku"; };
         };
diff --git a/waku/v2/protocol/relay/waku_relay.go b/waku/v2/protocol/relay/waku_relay.go
index a6f9a1692..06fd2c281 100644
--- a/waku/v2/protocol/relay/waku_relay.go
+++ b/waku/v2/protocol/relay/waku_relay.go
@@ -286,8 +286,8 @@ func (w *WakuRelay) Publish(ctx context.Context, message *pb.WakuMessage, opts .
 		return nil, errors.New("not enough peers to publish")
 	}
 
-	w.topicsMutex.RLock()
-	defer w.topicsMutex.RUnlock()
+	w.topicsMutex.Lock()
+	defer w.topicsMutex.Unlock()
 
 	pubSubTopic, err := w.upsertTopic(params.pubsubTopic)
 	if err != nil {