diff --git a/mps/tool/testrun.sh b/mps/tool/testrun.sh
index 1bdaf0aa6d2..5fdfa47bc05 100755
--- a/mps/tool/testrun.sh
+++ b/mps/tool/testrun.sh
@@ -1,4 +1,4 @@
-#!/bin/sh
+#!/usr/bin/env bash
 # 
 # $Id$
 # Copyright (c) 2013-2014 Ravenbrook Limited. See end of file for license.