diff --git a/modules/ppcp-webhooks/src/Handler/PaymentSaleCompleted.php b/modules/ppcp-webhooks/src/Handler/PaymentSaleCompleted.php
index 54d63f2b1..6f5cb491d 100644
--- a/modules/ppcp-webhooks/src/Handler/PaymentSaleCompleted.php
+++ b/modules/ppcp-webhooks/src/Handler/PaymentSaleCompleted.php
@@ -94,7 +94,7 @@ class PaymentSaleCompleted implements RequestHandler {
 		foreach ( $subscriptions as $subscription ) {
 			$parent_order   = wc_get_order( $subscription->get_parent() );
 			$transaction_id = wc_clean( wp_unslash( $request['resource']['id'] ?? '' ) );
-			if ( $transaction_id && is_a( $parent_order, WC_Order::class ) ) {
+			if ( $transaction_id && is_string( $transaction_id ) && is_a( $parent_order, WC_Order::class ) ) {
 				$this->update_transaction_id( $transaction_id, $parent_order, $this->logger );
 			}
 		}
diff --git a/modules/ppcp-webhooks/src/Handler/PaymentSaleRefunded.php b/modules/ppcp-webhooks/src/Handler/PaymentSaleRefunded.php
index 99679f477..ff3c1dc6a 100644
--- a/modules/ppcp-webhooks/src/Handler/PaymentSaleRefunded.php
+++ b/modules/ppcp-webhooks/src/Handler/PaymentSaleRefunded.php
@@ -12,6 +12,7 @@ namespace WooCommerce\PayPalCommerce\Webhooks\Handler;
 use Psr\Log\LoggerInterface;
 use WooCommerce\PayPalCommerce\WcGateway\Processor\RefundMetaTrait;
 use WooCommerce\PayPalCommerce\WcGateway\Processor\TransactionIdHandlingTrait;
+use WP_Error;
 use WP_REST_Request;
 use WP_REST_Response;
 
@@ -100,7 +101,7 @@ class PaymentSaleRefunded implements RequestHandler {
 				)
 			);
 
-			if ( is_wp_error( $refund ) ) {
+			if ( $refund instanceof WP_Error ) {
 				$this->logger->warning(
 					sprintf(
 					// translators: %s is the order id.