diff --git a/t/t4030-diff-textconv.sh b/t/t4030-diff-textconv.sh
index 0b76e7c97..2f27a0ba9 100755
--- a/t/t4030-diff-textconv.sh
+++ b/t/t4030-diff-textconv.sh
@@ -29,7 +29,7 @@ test_expect_success 'setup binary file with history' '
 	printf "\\0\\n" >file &&
 	git add file &&
 	git commit -m one &&
-	printf "\\1\\n" >>file &&
+	printf "\\01\\n" >>file &&
 	git add file &&
 	git commit -m two
 '