diff --git a/generate-certs.sh b/generate-certs.sh
old mode 100644
new mode 100755
index 9773efa..2e81fde
--- a/generate-certs.sh
+++ b/generate-certs.sh
@@ -3,7 +3,13 @@
 echo ""
 
 #chdir to current dir.
-cd "$(dirname "$0")"
+cd "$(dirname "$0")" || exit
+
+#Check docker exist
+if ! [ -x "$(command -v docker)" ]; then
+  echo -e 'Error: Docker is not installed.\n'
+  exit 1
+fi
 
 #Load config
 config_file=$1