diff --git a/ulib/debian b/ulib/debian
index 4d2f8ca..5af08c5 100644
--- a/ulib/debian
+++ b/ulib/debian
@@ -1094,7 +1094,7 @@ iface lo inet loopback
 
         network_fix_hostname "$host"
         network_fix_mailname "$host"
-        network_fix_hosts "$host" "$mainip" "$oldhost"
+        [ -n "$mainip" ] && network_fix_hosts "$host" "$mainip" "$oldhost"
 
         eend
     fi