diff --git a/seafile/rootfs/defaults/.env.example b/seafile/rootfs/defaults/.env.example
index 810e45c5f..86e9b5dd1 100644
--- a/seafile/rootfs/defaults/.env.example
+++ b/seafile/rootfs/defaults/.env.example
@@ -25,7 +25,7 @@ USE_HTTPS=1
 MYSQL_HOST=db
 MYSQL_USER_PASSWD=secret
 MYSQL_ROOT_PASSWD=secret
-
+MYSQL_PORT=3306
 
 ### Volume parameters