diff --git a/EduNetworkBuilder/ListBoxWindow.cs b/EduNetworkBuilder/ListBoxWindow.cs
index c1a48e1..6f8bd78 100644
--- a/EduNetworkBuilder/ListBoxWindow.cs
+++ b/EduNetworkBuilder/ListBoxWindow.cs
@@ -755,7 +755,10 @@ namespace EduNetworkBuilder
         {
             NB_IPAddress newip = new NB_IPAddress(NB.ZeroIPString, NB.ZeroIPString, NB.ZeroIPString);
             newip.Edit(myNetDevice, this, NB.Translate("LBW_AddRouteCreate"));
-            myNetDevice.AddRoute(newip);
+            if (!newip.Equals(new NB_IPAddress(NB.ZeroIPString, NB.ZeroIPString, NB.ZeroIPString)))
+            {
+                myNetDevice.AddRoute(newip);
+            }
             UpdateForm();
         }