diff --git a/classes/redis_store.php b/classes/redis_store.php
index baf82ef0d..b464430bc 100644
--- a/classes/redis_store.php
+++ b/classes/redis_store.php
@@ -81,7 +81,7 @@ public function set(string $type, string $key, $value, ?int $expire = null): voi
      * @param string $key
      * @return mixed|null
      */
-    public function get($type, $key) {
+    public function get($type, $key): mixed {
         $value = $this->redis->get($this->make_key($type, $key));
         if ($value === false) {
             $value = null;