diff --git a/t/t4029-diff-trailing-space.sh b/t/t4029-diff-trailing-space.sh
index 9ddbbcd..3ccc237 100755
--- a/t/t4029-diff-trailing-space.sh
+++ b/t/t4029-diff-trailing-space.sh
@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/bin/sh
 #
 # Copyright (c) Jim Meyering
 #