diff --git a/Documentation/git-am.txt b/Documentation/git-am.txt
index e080458d6c..463a3c6600 100644
--- a/Documentation/git-am.txt
+++ b/Documentation/git-am.txt
@@ -128,6 +128,9 @@ include::rerere-options.txt[]
 	These flags are passed to the 'git apply' (see linkgit:git-apply[1])
 	program that applies
 	the patch.
++
+Valid <action> for the `--whitespace` option are:
+`nowarn`, `warn`, `fix`, `error`, and `error-all`.
 
 --patch-format::
 	By default the command will try to detect the patch format
diff --git a/apply.c b/apply.c
index 355e2b0f2f..432837a674 100644
--- a/apply.c
+++ b/apply.c
@@ -77,7 +77,8 @@ static int parse_whitespace_option(struct apply_state *state, const char *option
 		return 0;
 	}
 	/*
-	 * Please update $__git_whitespacelist in git-completion.bash
+	 * Please update $__git_whitespacelist in git-completion.bash,
+	 * Documentation/git-apply.txt, and Documentation/git-am.txt
 	 * when you add new options.
 	 */
 	return error(_("unrecognized whitespace option '%s'"), option);