diff --git a/prepare_64bit_asio b/prepare_64bit_asio
index 62dd7f4..3bdc5e1 100755
--- a/prepare_64bit_asio
+++ b/prepare_64bit_asio
@@ -1,4 +1,4 @@
-#!/bin/sh
+#!/bin/bash
 ed -s asio.h <<< $'g/unsigned long/s//ULONG/g\nw\nq'
 ed -s asio.h <<< $'g/long long int/s//LONGLONG/g\nw\nq'
 ed -s asio.h <<< $'g/long int/s//LONG/g\nw\nq'