diff --git a/ext/autocomplete/main.php b/ext/autocomplete/main.php
index 0c7b7368..f8cb44c4 100644
--- a/ext/autocomplete/main.php
+++ b/ext/autocomplete/main.php
@@ -16,7 +16,7 @@ class AutoComplete extends Extension
 
         if ($event->page_matches("api/internal/autocomplete")) {
             $limit = (int)($_GET["limit"] ?? 0);
-            $s = $_GET["s"] ?? null;
+            $s = $_GET["s"] ?? "";
 
             $res = $this->complete($s, $limit);