diff --git a/piwik.admin.inc b/piwik.admin.inc
index 942a1d6..7caecae 100644
--- a/piwik.admin.inc
+++ b/piwik.admin.inc
@@ -389,14 +389,24 @@ function piwik_admin_settings_form_validate($form, &$form_state) {
     form_set_error('piwik_site_id', t('A valid Piwik site ID is an integer only.'));
   }
 
-  $url = $form_state['values']['piwik_url_http'] . 'piwik.php';
+  $piwik_url = $form_state['values']['piwik_url_http'];
+  if('/' != substr($piwik_url, -1, 1)) {
+    $piwik_url = $piwik_url . '/';
+    $form_state['values']['piwik_url_http'] = $piwik_url;
+  }
+  $url = $piwik_url . 'piwik.php';
   $result = drupal_http_request($url);
   if ($result->code != 200) {
     form_set_error('piwik_url_http', t('The validation of "@url" failed with error "@error" (HTTP code @code).', array('@url' => check_url($url), '@error' => $result->error, '@code' => $result->code)));
   }
 
   if (!empty($form_state['values']['piwik_url_https'])) {
-    $url = $form_state['values']['piwik_url_https'] . 'piwik.php';
+    $piwik_url = $form_state['values']['piwik_url_https'];
+    if('/' != substr($piwik_url, -1, 1)) {
+      $piwik_url = $piwik_url . '/';
+      $form_state['values']['piwik_url_https'] = $piwik_url;
+    }
+    $url = $piwik_url . 'piwik.php';
     $result = drupal_http_request($url);
     if ($result->code != 200) {
       form_set_error('piwik_url_https', t('The validation of "@url" failed with error "@error" (HTTP code @code).', array('@url' => check_url($url), '@error' => $result->error, '@code' => $result->code)));