diff --git a/advagg.install b/advagg.install
index cbbc008..abbaf56 100644
--- a/advagg.install
+++ b/advagg.install
@@ -589,7 +589,7 @@ function advagg_install_check_via_http(&$requirements) {
       }
       // Set arguments for drupal_http_request().
       // Make a 404 request to the advagg menu callback.
-      $url = file_create_url($path . '/' . $type . REQUEST_TIME . '.' . $type);
+      $url = file_create_url($path . '/' . $type . ADVAGG_SPACE . REQUEST_TIME . '.' . $type);
       // Set all timeouts to 12 seconds.
       $options = array(
         'timeout' => 12,