diff --git a/includes/gateway/class-omise-payment-mobilebanking.php b/includes/gateway/class-omise-payment-mobilebanking.php
index 03ec4eca..e35bfcaf 100644
--- a/includes/gateway/class-omise-payment-mobilebanking.php
+++ b/includes/gateway/class-omise-payment-mobilebanking.php
@@ -85,7 +85,7 @@ public function charge($order_id, $order)
 		);
 
 		$requestData['source'] = array_merge($requestData['source'], [
-			$requestData['platform_type'] = Omise_Util::get_platform_type(wc_get_user_agent())
+			'platform_type' => Omise_Util::get_platform_type(wc_get_user_agent())
 		]);
 		return OmiseCharge::create($requestData);
 	}