diff --git a/Documentation/git-rev-parse.txt b/Documentation/git-rev-parse.txt
index 7757abe621..5fcec19a56 100644
--- a/Documentation/git-rev-parse.txt
+++ b/Documentation/git-rev-parse.txt
@@ -89,6 +89,10 @@ OPTIONS
 --git-dir::
 	Show `$GIT_DIR` if defined else show the path to the .git directory.
 
+--is-inside-git-dir::
+	When the current working directory is below the repository
+	directory print "true", otherwise "false".
+
 --short, --short=number::
 	Instead of outputting the full SHA1 values of object names try to
 	abbreviate them to a shorter unique name. When no length is specified