diff --git a/docker/middleware.env.example b/docker/middleware.env.example
index f261d88d48..2eba62f594 100644
--- a/docker/middleware.env.example
+++ b/docker/middleware.env.example
@@ -1,7 +1,7 @@
 # ------------------------------
 # Environment Variables for db Service
 # ------------------------------
-PGUSER=postgres
+POSTGRES_USER=postgres
 # The password for the default postgres user.
 POSTGRES_PASSWORD=difyai123456
 # The name of the default postgres database.