diff --git a/docker-compose.yml b/docker-compose.yml
index 8e6a2f46be..6eefed8965 100644
--- a/docker-compose.yml
+++ b/docker-compose.yml
@@ -7,7 +7,7 @@ services:
     volumes:
       - ./:/usr/src/app
     ports:
-      - ${XTERMJS_PORT:3000}:3000
+      - ${XTERMJS_PORT:-3000}:3000
     command: ["npm", "start"]
 
   watch: