diff --git a/modules/ppcp-api-client/src/Repository/PartnerReferralsData.php b/modules/ppcp-api-client/src/Repository/PartnerReferralsData.php
index fd93e57be..af8bae174 100644
--- a/modules/ppcp-api-client/src/Repository/PartnerReferralsData.php
+++ b/modules/ppcp-api-client/src/Repository/PartnerReferralsData.php
@@ -136,9 +136,8 @@ class PartnerReferralsData {
 	 * @return array
 	 */
 	public function append_onboarding_token( array $data, string $token ): array {
-		$separator = strpos( $data['partner_config_override']['return_url'], '?' ) === false ? '?' : '&';
-
-		$data['partner_config_override']['return_url'] .= $separator . 'ppcpToken=' . $token;
+		$data['partner_config_override']['return_url'] =
+			add_query_arg( 'ppcpToken', $token, $data['partner_config_override']['return_url'] );
 		return $data;
 	}
 }
diff --git a/modules/ppcp-onboarding/src/Exception/RuntimeException.php b/modules/ppcp-onboarding/src/Exception/RuntimeException.php
deleted file mode 100644
index fc14fc94f..000000000
--- a/modules/ppcp-onboarding/src/Exception/RuntimeException.php
+++ /dev/null
@@ -1,18 +0,0 @@
-<?php
-/**
- * The modules Runtime Exception.
- *
- * @package WooCommerce\PayPalCommerce\Onboarding\Exception
- */
-
-declare(strict_types=1);
-
-namespace WooCommerce\PayPalCommerce\Onboarding\Exception;
-
-/**
- * Class RuntimeException
- */
-class RuntimeException extends \RuntimeException {
-
-
-}
diff --git a/modules/ppcp-onboarding/src/Helper/OnboardingUrl.php b/modules/ppcp-onboarding/src/Helper/OnboardingUrl.php
index ed3a2db18..3365882ad 100644
--- a/modules/ppcp-onboarding/src/Helper/OnboardingUrl.php
+++ b/modules/ppcp-onboarding/src/Helper/OnboardingUrl.php
@@ -10,7 +10,7 @@ declare(strict_types=1);
 namespace WooCommerce\PayPalCommerce\Onboarding\Helper;
 
 use WooCommerce\PayPalCommerce\ApiClient\Helper\Cache;
-use WooCommerce\PayPalCommerce\Onboarding\Exception\RuntimeException;
+use RuntimeException;
 
 /**
  * Class OnboardingUrl
diff --git a/modules/ppcp-wc-gateway/src/Settings/SettingsListener.php b/modules/ppcp-wc-gateway/src/Settings/SettingsListener.php
index 8e00e40c4..175333216 100644
--- a/modules/ppcp-wc-gateway/src/Settings/SettingsListener.php
+++ b/modules/ppcp-wc-gateway/src/Settings/SettingsListener.php
@@ -170,7 +170,7 @@ class SettingsListener {
 	/**
 	 * Listens if the merchant ID should be updated.
 	 */
-	public function listen_for_merchant_id() {
+	public function listen_for_merchant_id(): void {
 		if ( ! $this->is_valid_site_request() ) {
 			return;
 		}
diff --git a/tests/PHPUnit/Onboarding/Helper/OnboardingUrlTest.php b/tests/PHPUnit/Onboarding/Helper/OnboardingUrlTest.php
index 63b495792..5dadd2c79 100644
--- a/tests/PHPUnit/Onboarding/Helper/OnboardingUrlTest.php
+++ b/tests/PHPUnit/Onboarding/Helper/OnboardingUrlTest.php
@@ -5,7 +5,7 @@ namespace WooCommerce\PayPalCommerce\Onboarding\Helper;
 
 use PHPUnit\Framework\TestCase;
 use WooCommerce\PayPalCommerce\ApiClient\Helper\Cache;
-use WooCommerce\PayPalCommerce\Onboarding\Exception\RuntimeException;
+use RuntimeException;
 use function Brain\Monkey\Functions\when;
 
 class OnboardingUrlTest extends TestCase