diff --git a/tools/mod2spec.sh b/tools/mod2spec.sh
index 74b3021bf..98c0805ae 100755
--- a/tools/mod2spec.sh
+++ b/tools/mod2spec.sh
@@ -1,4 +1,4 @@
-#!/bin/sh
+#!/bin/bash
 set -eu
 
 echo "spec/${1//./_}_spec.lua"