diff --git a/bin/tests/system/ifconfig.sh.in b/bin/tests/system/ifconfig.sh.in
index a729055e22..126777c658 100755
--- a/bin/tests/system/ifconfig.sh.in
+++ b/bin/tests/system/ifconfig.sh.in
@@ -66,7 +66,7 @@ up() {
         [ "$aaaa" ] && ip address add $aaaa/64 dev lo
         ip link set dev lo:$int mtu 1500
       else
-        ifconfig lo:$int $a up netmask 255.255.255.0 mtu 1500
+        [ "$a" ] && ifconfig lo:$int $a up netmask 255.255.255.0 mtu 1500
         [ "$aaaa" ] && ifconfig lo inet6 add $aaaa/64
       fi
       ;;