diff --git a/cd.sh b/cd.sh
index 85e8ed4..87f418e 100644
--- a/cd.sh
+++ b/cd.sh
@@ -73,7 +73,7 @@ echo "CD_PROJECT_URL = ${CD_PROJECT_URL}"
 
 function cd_step {
     if [ "${1}" ] ; then
-        ((CD_STEP++))
+        CD_STEP=$((CD_STEP+1))
         echo "
  ↕ ${CD_STEP} ↔ ${1}
 "