diff --git a/exampleYmlFiles/docker-compose-latest-ultra-lite-security.yml b/exampleYmlFiles/docker-compose-latest-ultra-lite-security.yml
index 7971eeb7..b7848696 100644
--- a/exampleYmlFiles/docker-compose-latest-ultra-lite-security.yml
+++ b/exampleYmlFiles/docker-compose-latest-ultra-lite-security.yml
@@ -21,7 +21,7 @@ services:
     environment:
       DOCKER_ENABLE_SECURITY: "true"
       SECURITY_ENABLELOGIN: "true"
-      SYSTEM_DEFAULTLOCALE: en_US
+      SYSTEM_DEFAULTLOCALE: en-US
       UI_APPNAME: Stirling-PDF-Lite
       UI_HOMEDESCRIPTION: Demo site for Stirling-PDF-Lite Latest with Security
       UI_APPNAMENAVBAR: Stirling-PDF-Lite Latest