diff --git a/src/Loggers/AbstractModelLogger.php b/src/Loggers/AbstractModelLogger.php
index 7aa53eb..36d26b3 100644
--- a/src/Loggers/AbstractModelLogger.php
+++ b/src/Loggers/AbstractModelLogger.php
@@ -29,7 +29,7 @@ protected function getModelName(Model $model)
     }
 
 
-    protected function activityLogger(string $logName = null): ActivityLogger
+    protected function activityLogger(?string $logName = null): ActivityLogger
     {
         $defaultLogName = $this->getLogName();