diff --git a/t/t4212-log-corrupt.sh b/t/t4212-log-corrupt.sh
index e89e1f54b6..8b5433ea74 100755
--- a/t/t4212-log-corrupt.sh
+++ b/t/t4212-log-corrupt.sh
@@ -8,8 +8,9 @@ TEST_PASSES_SANITIZE_LEAK=true
 test_expect_success 'setup' '
 	test_commit foo &&
 
-	git cat-file commit HEAD |
-	sed "/^author /s/>/>-<>/" >broken_email.commit &&
+	git cat-file commit HEAD >ok.commit &&
+	sed "/^author /s/>/>-<>/" <ok.commit >broken_email.commit &&
+
 	git hash-object --literally -w -t commit broken_email.commit >broken_email.hash &&
 	git update-ref refs/heads/broken_email $(cat broken_email.hash)
 '