diff --git a/Shorewall/Perl/prog.footer b/Shorewall/Perl/prog.footer
index 4dde335b9..7003a51b0 100644
--- a/Shorewall/Perl/prog.footer
+++ b/Shorewall/Perl/prog.footer
@@ -33,25 +33,25 @@ usage() {
 }
 
 checkkernelversion() {
+?if __IPV6
     local kernel
 
-    if [ $g_family -eq 6 ]; then
-	kernel=$(uname -r 2> /dev/null | sed -e 's/-.*//')
+    kernel=$(uname -r 2> /dev/null | sed -e 's/-.*//')
 
-	case "$kernel" in
-	    *.*.*)
-		kernel=$(printf "%d%02d%02d" $(echo $kernel | sed -e 's/^\([0-9][0-9]*\)\.\([0-9][0-9]*\)\.\([0-9][0-9]*\).*$/\1 \2 \3/g'))
-		;;
-	    *)
-		kernel=$(printf "%d%02d00" $(echo $kernel | sed -e 's/^\([0-9][0-9]*\)\.\([0-9][0-9]*\).*$/\1 \2/g'))
-		;;
-	esac
+    case "$kernel" in
+	*.*.*)
+	    kernel=$(printf "%d%02d%02d" $(echo $kernel | sed -e 's/^\([0-9][0-9]*\)\.\([0-9][0-9]*\)\.\([0-9][0-9]*\).*$/\1 \2 \3/g'))
+	    ;;
+	*)
+	    kernel=$(printf "%d%02d00" $(echo $kernel | sed -e 's/^\([0-9][0-9]*\)\.\([0-9][0-9]*\).*$/\1 \2/g'))
+	    ;;
+    esac
 
-	if [ $kernel -lt 20624 ]; then
-	    error_message "ERROR: $g_product requires Linux kernel 2.6.24 or later"
-	    return 1
-	fi
+    if [ $kernel -lt 20624 ]; then
+	error_message "ERROR: $g_product requires Linux kernel 2.6.24 or later"
+	return 1
     fi
+?endif
 
     return 0
 }