diff --git a/salt/common/tools/sbin/soup b/salt/common/tools/sbin/soup
index d47c0f834..d2205842c 100755
--- a/salt/common/tools/sbin/soup
+++ b/salt/common/tools/sbin/soup
@@ -200,7 +200,8 @@ verify_latest_update_script() {
 while getopts ":b" opt; do
   case ${opt} in
     b ) # process option b
-      if [[ $OPTARG =~ '^[0-9]+$' ]]; then
+      re='^[0-9]+$'
+      if [[ $OPTARG =~ $re ]]; then
         BATCHSIZE=$OPTARG
       else
         echo "Batch size must be a number greater than 0"