diff --git a/tests.sh b/tests.sh
index b4a7fed..c136acb 100755
--- a/tests.sh
+++ b/tests.sh
@@ -1,4 +1,4 @@
-#!/usr/bin/env sh
+#!/usr/bin/env bash
 
 if [[ ! "$STACK" ]]; then
     echo '$STACK must be set! (heroku-16 | cedar-14)'