diff --git a/Documentation/cmd-set-reviewers.txt b/Documentation/cmd-set-reviewers.txt
index 5e367c6df4..f6248c68a6 100644
--- a/Documentation/cmd-set-reviewers.txt
+++ b/Documentation/cmd-set-reviewers.txt
@@ -28,6 +28,10 @@ API, as well as with the commit SHA-1 (at least the 7 first characters).
 -p::
 	Name of the project the intended change is contained within.  This
 	option must be supplied before Change-Id in order to take effect.
+	Please note that the project specified must be active.
+
+	If omitted, the impacted changes can be from different projects and
+	the current user needs to be authorized to set reviewers to all of them.
 
 --add::
 -a::