diff --git a/code/extensions/SiteTreeSubsites.php b/code/extensions/SiteTreeSubsites.php
index 1351b02..60afa20 100644
--- a/code/extensions/SiteTreeSubsites.php
+++ b/code/extensions/SiteTreeSubsites.php
@@ -33,7 +33,7 @@ class SiteTreeSubsites extends DataExtension
         if (Subsite::$disable_subsite_filter) {
             return;
         }
-        if ($dataQuery->getQueryParam('Subsite.filter') === false) {
+        if ($dataQuery && $dataQuery->getQueryParam('Subsite.filter') === false) {
             return;
         }