diff --git a/scripts/install b/scripts/install
index b776a15..3a61141 100644
--- a/scripts/install
+++ b/scripts/install
@@ -69,7 +69,7 @@ sudo sed -i "s/yunobase/$db_user/g" $final_path/syncserver.ini
 cd $final_path && sudo make build && sudo ./local/bin/easy_install gunicorn
 
 # Disable swapfile
-if [ -z "$tmp_swap_file" ];
+if [ -z ${tmp_swap_file+x} ];
 then
         sudo swapoff $tmp_swap_file
         sudo rm -f $tmp_swap_file