diff --git a/drush.php b/drush.php
index 1650f41..a5e91f8 100755
--- a/drush.php
+++ b/drush.php
@@ -10,7 +10,9 @@
 
 require(dirname(__FILE__) . '/includes/bootstrap.inc');
 
-drush_bootstrap_prepare();
+if (drush_bootstrap_prepare() === FALSE) {
+  exit(1);
+}
 exit(drush_main());
 
 /**
diff --git a/includes/bootstrap.inc b/includes/bootstrap.inc
index 73bcff2..b10bd73 100644
--- a/includes/bootstrap.inc
+++ b/includes/bootstrap.inc
@@ -1004,13 +1004,13 @@ function drush_bootstrap_prepare() {
 
   // Terminate immediately unless invoked as a command line script
   if (!drush_verify_cli()) {
-    die('drush is designed to run via the command line.');
+    return drush_set_error('DRUSH_REQUIREMENTS_ERROR', dt('drush is designed to run via the command line.'));
   }
 
   // Check supported version of PHP.
   define('DRUSH_MINIMUM_PHP', '5.3.5');
   if (version_compare(phpversion(), DRUSH_MINIMUM_PHP) < 0) {
-    die('Your command line PHP installation is too old. Drush requires at least PHP ' . DRUSH_MINIMUM_PHP . "\n");
+    return drush_set_error('DRUSH_REQUIREMENTS_ERROR', dt('Your command line PHP installation is too old. Drush requires at least PHP !version.', array('!version' => DRUSH_MINIMUM_PHP)));
   }
 
   $drush_info = drush_read_drush_info();