diff --git a/salt/manager/tools/sbin/soup b/salt/manager/tools/sbin/soup
index 06ce1757b..e29a6811e 100755
--- a/salt/manager/tools/sbin/soup
+++ b/salt/manager/tools/sbin/soup
@@ -314,7 +314,7 @@ disable_logstash_heavynodes() {
   for file in /opt/so/saltstack/local/pillar/minions/*.sls; do
     if [[ "$file" =~ "_heavynode.sls" && ! "$file" =~ "/opt/so/saltstack/local/pillar/minions/adv_" ]]; then
       if [ "$c" -eq 0 ]; then
-        ((c++))
+        c=$((c + 1))
         FINAL_MESSAGE_QUEUE+=("Logstash has been disabled on all heavynodes. It can be re-enabled via Grid Configuration in SOC.")
       fi
       echo "Disabling Logstash for: $file"