diff --git a/doc/git-annex-preferred-content.mdwn b/doc/git-annex-preferred-content.mdwn
index b23e9677fd..70d2723524 100644
--- a/doc/git-annex-preferred-content.mdwn
+++ b/doc/git-annex-preferred-content.mdwn
@@ -297,7 +297,7 @@ elsewhere to allow removing it).
   Note that `not balanced` is a bad thing to put in a preferred content
   expression for the same reason `not present` is.
 
-* `fullybalanced=groupname`
+* `fullybalanced=groupname[:number]`
 
   This is like `balanced`, but allows moving content between repositories
   in the group at any time to keep it fully balanced.