diff --git a/src/ET_Client.php b/src/ET_Client.php
index b06bbb0..e0d5036 100755
--- a/src/ET_Client.php
+++ b/src/ET_Client.php
@@ -386,10 +386,10 @@ function createPayloadForOauth2(){
             $payload->grant_type = 'client_credentials';
 		}
 
-		if (!empty(trim($this->accountId))){
+		if (!empty(trim($this->accountId ?? ''))){
             $payload->account_id = $this->accountId;
 		}
-		if (!empty(trim($this->scope))){
+		if (!empty(trim($this->scope ?? ''))){
             $payload->scope = $this->scope;
 		}