diff --git a/drupalvb.inc.php b/drupalvb.inc.php
index 75f6c96..5f14494 100644
--- a/drupalvb.inc.php
+++ b/drupalvb.inc.php
@@ -296,9 +296,12 @@ function drupalvb_get_options() {
  *     PHP comment lines of config.php.
  */
 function drupalvb_get_config() {
-  static $config = array();
+  static $config;
+
+  if (!isset($config)) {
+    $config = array();
+    $config['version'] = NULL;
 
-  if (empty($config)) {
     // @todo Find & include vB's config automatically?
     // $files = file_scan_directory('.', '^config.php$', $nomask = array('.', '..', 'CVS', '.svn'));
     $config_file = drupal_get_path('module', 'drupalvb') . '/config.php';
@@ -308,7 +311,6 @@ function drupalvb_get_config() {
       // Additionally parse the vBulletin version out of the php file header, as
       // some integration functionality needs to account for API changes in
       // later vBulletin versions.
-      $config['version'] = NULL;
       $file = fopen($config_file, 'r');
       $max_lines = 10;
       while ($max_lines && $line = fgets($file, 30)) {
diff --git a/drupalvb.install b/drupalvb.install
index 30af0e2..9fff731 100644
--- a/drupalvb.install
+++ b/drupalvb.install
@@ -1,6 +1,31 @@
 <?php
 
 /**
+ * Implements hook_requirements().
+ */
+function drupalvb_requirements($phase) {
+  // Ensure translations don't break at install time.
+  $t = get_t();
+
+  module_load_include('inc.php', 'drupalvb');
+  $vb_config = drupalvb_get_config();
+
+  $requirements['drupalvb'] = array(
+    'title' => 'vBulletin version',
+    'value' => $vb_config['version'],
+  );
+  if (empty($vb_config['version'])) {
+    $requirements['drupalvb']['value'] = $t('Missing');
+    $requirements['drupalvb']['severity'] = REQUIREMENT_ERROR;
+    $requirements['drupalvb']['description'] = $t('The vBulletin configuration file <code>@filepath-vb</code> is required in <code>@filepath-drupalvb</code> (either as copy or soft link).', array(
+      '@filepath-vb' => 'includes/config.php',
+      '@filepath-drupalvb' => drupal_get_path('module', 'drupalvb') . '/config.php',
+    ));
+  }
+  return $requirements;
+}
+
+/**
  * Implementation of hook_schema().
  */
 function drupalvb_schema() {