diff --git a/src/Consumer/Consumer.php b/src/Consumer/Consumer.php
index 34020a8..2a03685 100644
--- a/src/Consumer/Consumer.php
+++ b/src/Consumer/Consumer.php
@@ -126,7 +126,7 @@ public function getQueue(): Queue
         return $queue;
     }
 
-    public function handle(Closure $messageHandler, Closure $emptyHandler = null, bool $ack = true): int
+    public function handle(Closure $messageHandler, ?Closure $emptyHandler = null, bool $ack = true): int
     {
         $queue = $this->create()->getQueue();
         $iterations = $this->getIterations();