diff --git a/t/t1509-root-work-tree.sh b/t/t1509-root-work-tree.sh
index 553a3f601ba..eb57fe7e19f 100755
--- a/t/t1509-root-work-tree.sh
+++ b/t/t1509-root-work-tree.sh
@@ -221,7 +221,8 @@ test_expect_success 'setup' '
 	rm -rf /.git &&
 	echo "Initialized empty Git repository in /.git/" > expected &&
 	git init > result &&
-	test_cmp expected result
+	test_cmp expected result &&
+	git config --global --add safe.directory /
 '
 
 test_vars 'auto gitdir, root' ".git" "/" ""