diff --git a/Shorewall/Perl/lib.runtime b/Shorewall/Perl/lib.runtime
index 14265b652..de0c38933 100644
--- a/Shorewall/Perl/lib.runtime
+++ b/Shorewall/Perl/lib.runtime
@@ -421,7 +421,7 @@ restore_default_route() # $1 = USE_DEFAULT_RT
 conditionally_flush_conntrack() {
 
     if [ -n "$g_purge" ]; then
-	if [ -n $(mywhich conntrack) ]; then
+	if [ -n "$(mywhich conntrack)" ]; then
             conntrack -F
 	else
             error_message "WARNING: The '-p' option requires the conntrack utility which does not appear to be installed on this system"