diff --git a/modules/system/system.install b/modules/system/system.install
index 19908ee0d102a9e4f2dcd007546fa5cceb32dbf8..46d4deaa2bdc9ead029bb1274ca4a3e7133936f2 100644
--- a/modules/system/system.install
+++ b/modules/system/system.install
@@ -42,6 +42,17 @@ function system_requirements($phase) {
     $requirements['php']['severity'] = REQUIREMENT_ERROR;
   }
 
+  // Make sure the tokenizer extension is enabled, which is required by the code registry.
+  $requirements['php_tokenizer'] = array(
+    'title' => $t('PHP tokenizer'),
+    'value' => $t('Enabled'),
+  );
+  if (!function_exists('token_get_all')) {
+    $requirements['php_tokenizer']['value'] = $t('Not enabled');
+    $requirements['php_tokenizer']['description'] = $t('Drupal requires the <a href="@url">tokenizer extension</a> to be enabled.', array('@url' => 'http://php.net/tokenizer'));
+    $requirements['php_tokenizer']['severity'] = REQUIREMENT_ERROR;
+  }
+
   // Test PHP register_globals setting.
   $requirements['php_register_globals'] = array(
     'title' => $t('PHP register globals'),