diff --git a/eth/catalyst/simulated_beacon.go b/eth/catalyst/simulated_beacon.go
index de6ab8e6bd..86355a1533 100644
--- a/eth/catalyst/simulated_beacon.go
+++ b/eth/catalyst/simulated_beacon.go
@@ -54,11 +54,10 @@ type newWithdrawalsEvent struct{ Withdrawals types.Withdrawals }
 // add queues a withdrawal for future inclusion.
 func (w *withdrawalQueue) add(withdrawal *types.Withdrawal) error {
 	w.mu.Lock()
-	defer w.mu.Unlock()
-
 	w.pending = append(w.pending, withdrawal)
-	w.feed.Send(newWithdrawalsEvent{types.Withdrawals{withdrawal}})
+	w.mu.Unlock()
 
+	w.feed.Send(newWithdrawalsEvent{types.Withdrawals{withdrawal}})
 	return nil
 }
 
diff --git a/eth/catalyst/simulated_beacon_api.go b/eth/catalyst/simulated_beacon_api.go
index da95be18d3..79a0121b5b 100644
--- a/eth/catalyst/simulated_beacon_api.go
+++ b/eth/catalyst/simulated_beacon_api.go
@@ -54,7 +54,8 @@ func (a *simulatedBeaconAPI) loop() {
 	)
 	defer newTxsSub.Unsubscribe()
 	defer newWxsSub.Unsubscribe()
-	// a background thread which signals to the simulator when to commit
+
+	// A background thread which signals to the simulator when to commit
 	// based on messages over doCommit.
 	go func() {
 		for _ = range doCommit {