diff --git a/kubernetes/contrib/tools/rke/rke_setup.sh b/kubernetes/contrib/tools/rke/rke_setup.sh
index 7950e0c..2ee123b 100755
--- a/kubernetes/contrib/tools/rke/rke_setup.sh
+++ b/kubernetes/contrib/tools/rke/rke_setup.sh
@@ -344,7 +344,7 @@
     esac
 done
 
-if [[ -z $BRANCH ]]; then
+if [ -z $BRANCH ]; then
   usage
   exit 1
 fi