diff --git a/files/certbot-renewal.sh b/files/certbot-renewal.sh
index 52dff70..a5d87fb 100644
--- a/files/certbot-renewal.sh
+++ b/files/certbot-renewal.sh
@@ -7,7 +7,7 @@ for f in `ls /etc/letsencrypt/live/ --ignore "README"`
 do
     echo Checking $f >> $log
     #check if cert has already expired or will expire within the next two days and renew if applicable
-    expires=`echo `openssl x509 -enddate -noout -in /etc/letsencrypt/live/$f/cert.pem` " - 2 day" | grep -Po "(?<=notAfter=).*" | date +%Y%m%d -f -`
+    expires=$(echo `openssl x509 -enddate -noout -in /etc/letsencrypt/live/$f/cert.pem` " - 2 day" | grep -Po "(?<=notAfter=).*" | date +%Y%m%d -f -)
     if [[ $today > $expires ]]
     then
         echo Certificate for $f is expired, renewing >> $log