diff --git a/template.php b/template.php
index 52068b8..a8fe76b 100644
--- a/template.php
+++ b/template.php
@@ -171,3 +171,32 @@ function rijkshuisstijl_breadcrumb(&$variables) {
     return $output;
   }
 }
+
+/**
+ * Implements theme_link().
+ *
+ * Override links to add an 'external' class if needed.
+ *
+ * Adds the external class to external links that
+ * don't contain an image.
+ *
+ */
+function rijkshuisstijl_link($variables) {
+  global $base_url;
+  if (url_is_external($variables['path'])
+    && strstr($variables['path'], $base_url) === FALSE
+    && strstr($variables['text'], '<img ') === FALSE) {
+
+    $variables['options']['attributes']['class'][] = 'external';
+    $variables['options']['html'] = TRUE;
+
+    if (!empty($variables['options']['attributes']['title'])) {
+      $title = &$variables['options']['attributes']['title'];
+      $title = t('@title (Opens an external page)', array('@title' => $title));
+    }
+    else {
+      $variables['options']['attributes']['title'] = t('(Opens an external page)');
+    }
+  }
+  return '<a href="' . check_plain(url($variables['path'], $variables['options'])) . '"' . drupal_attributes($variables['options']['attributes']) . '>' . ($variables['options']['html'] ? $variables['text'] : check_plain($variables['text'])) . '</a>';
+}