diff --git a/plugins/RedisCache/RedisCachePlugin.php b/plugins/RedisCache/RedisCachePlugin.php
index f2284dd8cd..072295a2f6 100644
--- a/plugins/RedisCache/RedisCachePlugin.php
+++ b/plugins/RedisCache/RedisCachePlugin.php
@@ -93,7 +93,7 @@ class RedisCachePlugin extends Plugin
             return true;
         }
 
-        if (is_int($ret) || $ret->getPayload() === "OK") {
+        if (is_int($ret) || (!is_null($ret) && $ret->getPayload() === "OK")) {
             $success = true;
             return false;
         }