diff --git a/Documentation/git-format-patch.txt b/Documentation/git-format-patch.txt
index dfcc7da4c2..ed299e077d 100644
--- a/Documentation/git-format-patch.txt
+++ b/Documentation/git-format-patch.txt
@@ -173,8 +173,7 @@ series, where the head is chosen from the cover letter, the
 threading makes every mail a reply to the previous one.
 +
 The default is `--no-thread`, unless the `format.thread` configuration
-is set.  If `--thread` is specified without a style, it defaults to the
-style specified by `format.thread` if any, or else `shallow`.
+is set.  `--thread` without an argument is equivalent to `--thread=shallow`.
 +
 Beware that the default for 'git send-email' is to thread emails
 itself.  If you want `git format-patch` to take care of threading, you
diff --git a/t/t4014-format-patch.sh b/t/t4014-format-patch.sh
index 8c3d06622a..b27a72f78a 100755
--- a/t/t4014-format-patch.sh
+++ b/t/t4014-format-patch.sh
@@ -470,6 +470,11 @@ test_expect_success 'thread' '
 	check_threading expect.thread --thread main
 '
 
+test_expect_success '--thread overrides format.thread=deep' '
+	test_config format.thread deep &&
+	check_threading expect.thread --thread main
+'
+
 cat >expect.in-reply-to <<EOF
 ---
 Message-Id: <0>