diff --git a/inc/config.php b/inc/config.php
index e1c02b96..6bfa38b1 100644
--- a/inc/config.php
+++ b/inc/config.php
@@ -121,10 +121,10 @@ public static function init( $service_settings = [] ) {
 			self::$secret = trim( $service_settings['secret'] );
 		}
 		self::$service_url = sprintf( 'https://%s.%s', self::$key, self::$base_domain );
-		if ( isset( $service_settings['domain'] ) && ! empty( $service_settings['domain'] ) ) {
-			self::$service_url = sprintf( 'https://%s', $service_settings['domain'] );
-		} elseif ( defined( 'OPTML_CUSTOM_DOMAIN' ) ) {
+		if ( defined( 'OPTML_CUSTOM_DOMAIN' ) ) {
 			self::$service_url = constant( 'OPTML_CUSTOM_DOMAIN' );
+		} elseif ( isset( $service_settings['domain'] ) && ! empty( $service_settings['domain'] ) ) {
+			self::$service_url = sprintf( 'https://%s', $service_settings['domain'] );
 		}
 
 		$options = [ 'domain' => parse_url( self::$service_url, PHP_URL_HOST ) ];