diff --git a/restore.sh b/restore.sh
index a7e1b4c..a7550ef 100644
--- a/restore.sh
+++ b/restore.sh
@@ -54,7 +54,7 @@ done
 #get swap size
 swapSize=$(free -m | grep "Mem" | awk '{print $2}')
 read -p "Enter extra amount of swap (empty == 512):" swapExtra
-if [ -z "$swapExtra" ] && swapExtra=512
+[[ -z "$swapExtra" ]] && swapExtra=512
 let "swapSize += swapExtra" #add 512 mbs to swap for swap, not only hibernation
 swapSize=$swapSize"M"