diff --git a/engine/reference/builder.md b/engine/reference/builder.md
index 6db16b567e..75cacb1913 100644
--- a/engine/reference/builder.md
+++ b/engine/reference/builder.md
@@ -1204,8 +1204,8 @@ into the newly created volume.
 
 The `USER` instruction sets the user name or UID to use when running the image
 and for any `RUN`, `CMD` and `ENTRYPOINT` instructions that follow it in the
-`Dockerfile`. Optionaly a group name can be set by adding a `:` and a GID, which will be used as the GID 
-for `RUN`, `CMD` and `ENTRYPOINT` instructions.
+`Dockerfile`. To specify the group ID (GID), add it as a suffix to the UID, 
+separated by a colon. For instance, `MYUSER:MYGROUP`.
 
 ## WORKDIR