diff --git a/Documentation/git-update-index.txt b/Documentation/git-update-index.txt
index 1a296bc29a..3df9c26f44 100644
--- a/Documentation/git-update-index.txt
+++ b/Documentation/git-update-index.txt
@@ -17,6 +17,7 @@ SYNOPSIS
 	     [--[no-]assume-unchanged]
 	     [--[no-]skip-worktree]
 	     [--ignore-submodules]
+	     [--[no-|force-]untracked-cache]
 	     [--really-refresh] [--unresolve] [--again | -g]
 	     [--info-only] [--index-info]
 	     [-z] [--stdin] [--index-version <n>]