diff --git a/debian/ngcp-rtpengine-iptables-setup b/debian/ngcp-rtpengine-iptables-setup
index 56cf87e38..3b9045db7 100755
--- a/debian/ngcp-rtpengine-iptables-setup
+++ b/debian/ngcp-rtpengine-iptables-setup
@@ -39,7 +39,7 @@ fi
 
 firewall_setup()
 {
-  if [ "$TABLE" -lt 0 ] || [ "$VIRT" = "yes" ]; then
+  if [ -z "$TABLE" ] || [ "$TABLE" -lt 0 ] || [ "$VIRT" = "yes" ]; then
     return
   fi
 
@@ -66,7 +66,7 @@ firewall_setup()
 
 firewall_teardown()
 {
-  if [ "$TABLE" -lt 0 ] || [ "$VIRT" = "yes" ]; then
+  if [ -z "$TABLE" ] || [ "$TABLE" -lt 0 ] || [ "$VIRT" = "yes" ]; then
     return
   fi
 
diff --git a/pkg/deb/debian/rtpengine-iptables-setup b/pkg/deb/debian/rtpengine-iptables-setup
index b024212ce..1c4363462 100755
--- a/pkg/deb/debian/rtpengine-iptables-setup
+++ b/pkg/deb/debian/rtpengine-iptables-setup
@@ -39,7 +39,7 @@ fi
 
 firewall_setup()
 {
-  if [ "$TABLE" -lt 0 ] || [ "$VIRT" = "yes" ]; then
+  if [ -z "$TABLE" ] || [ "$TABLE" -lt 0 ] || [ "$VIRT" = "yes" ]; then
     return
   fi
 
@@ -66,7 +66,7 @@ firewall_setup()
 
 firewall_teardown()
 {
-  if [ "$TABLE" -lt 0 ] || [ "$VIRT" = "yes" ]; then
+  if [ -z "$TABLE" ] || [ "$TABLE" -lt 0 ] || [ "$VIRT" = "yes" ]; then
     return
   fi