diff --git a/README.md b/README.md
index 17e04ec..fde01b2 100644
--- a/README.md
+++ b/README.md
@@ -28,6 +28,8 @@ services:
       POSTSIZE: 256M # default: 256M
       PUID: 1000 # default: 1000
       PGID: 1000 # default: 1000
+      USERNAME: theuser # default: theuser
+      GROUPNAME: thegroup # default: thegroup
       TZ: Etc/UTC  # default: Etc/UTC
       FPM_MAX_CHILDREN: 5 # default: 5
       FPM_START_SERVERS: 1 # default: 1