diff --git a/docker-entrypoint.sh b/docker-entrypoint.sh
index eda32f9..2a43d90 100755
--- a/docker-entrypoint.sh
+++ b/docker-entrypoint.sh
@@ -1,7 +1,7 @@
 #!/bin/bash
 set -e
 
-if [[ ! -z "${CUSTOM_CERT}" ]]; then
+if [ ! -z "${CUSTOM_CERT}" ]; then
   echo "Use custom certificate"
   if [ ! -f /cert/private.key ]; then
     echo "Generate new certificate"