diff --git a/t/t6101-rev-parse-parents.sh b/t/t6101-rev-parse-parents.sh
index 5f55ab98d3..7281889717 100755
--- a/t/t6101-rev-parse-parents.sh
+++ b/t/t6101-rev-parse-parents.sh
@@ -39,7 +39,8 @@ test_expect_success 'setup' '
 '
 
 test_expect_success 'start is valid' '
-	git rev-parse start | grep "^$OID_REGEX$"
+	git rev-parse start >actual &&
+	test_grep "^$OID_REGEX$" actual
 '
 
 test_expect_success 'start^0' '