diff --git a/bin/rbenv-install b/bin/rbenv-install
index 16302970..47af0ff4 100755
--- a/bin/rbenv-install
+++ b/bin/rbenv-install
@@ -1,2 +1,9 @@
-#!/bin/sh
-exec ruby-build $1 ~/.rbenv/versions/$1
+#!/usr/bin/env bash
+set -e
+[ -n "$RBENV_DEBUG" ] && set -x
+
+if [ -z "$RBENV_ROOT" ]; then
+  RBENV_ROOT="${HOME}/.rbenv"
+fi
+
+exec ruby-build "$1" "${RBENV_ROOT}/versions/$1"