diff --git a/t/t1600-index.sh b/t/t1600-index.sh
index 0ebbae1305..9368d82f7d 100755
--- a/t/t1600-index.sh
+++ b/t/t1600-index.sh
@@ -88,6 +88,7 @@ test_expect_success 'index.skipHash config option' '
 	git -c protocol.file.allow=always submodule add ./ sub &&
 	git config index.skipHash false &&
 	git -C sub config index.skipHash true &&
+	rm -f .git/modules/sub/index &&
 	>sub/file &&
 	git -C sub add a &&
 	test_trailing_hash .git/modules/sub/index >hash &&