diff --git a/src/Flow.cpp b/src/Flow.cpp
index db54d3d327bd..c66e8da470b8 100644
--- a/src/Flow.cpp
+++ b/src/Flow.cpp
@@ -304,7 +304,7 @@ void Flow::deferredInitialization() {
 
       Mac *srv_mac = srv_host->getMac();
       /* Add client gateway */
-      if (srv_mac && (!srv_host->isLocalHost())) {
+      if (srv_mac && !srv_mac->isNull() && !srv_host->isLocalHost()) {
         LocalHost *lh = (LocalHost *)cli_host;
         lh->setRouterMac(srv_mac);
       }