diff --git a/beacon-chain/sync/rpc_goodbye.go b/beacon-chain/sync/rpc_goodbye.go
index cda906204..0a0c83892 100644
--- a/beacon-chain/sync/rpc_goodbye.go
+++ b/beacon-chain/sync/rpc_goodbye.go
@@ -27,7 +27,10 @@ func (r *Service) goodbyeRPCHandler(ctx context.Context, msg interface{}, stream
 	defer cancel()
 	setRPCStreamDeadlines(stream)
 
-	m := msg.(uint64)
+	m, ok:= msg.(uint64)
+	if !ok {
+		return fmt.Errorf("wrong message type for goodbye, got %T, wanted uint64", msg)
+	}
 	log := log.WithField("Reason", goodbyeMessage(m))
 	log.WithField("peer", stream.Conn().RemotePeer()).Info("Peer has sent a goodbye message")
 	// closes all streams with the peer