diff --git a/src/Api/Actions/Posts/IndexAction.php b/src/Api/Actions/Posts/IndexAction.php
index c5dcbb27f..7bea440e9 100644
--- a/src/Api/Actions/Posts/IndexAction.php
+++ b/src/Api/Actions/Posts/IndexAction.php
@@ -61,6 +61,7 @@ class IndexAction extends SerializeCollectionAction
         if (count($postIds)) {
             $posts = $this->posts->findByIds($postIds, $user);
         } else {
+            $where = [];
             if ($discussionId = $request->get('discussions')) {
                 $where['discussion_id'] = $discussionId;
             }