diff --git a/core/core.services.yml b/core/core.services.yml
index 4563d66..e3ba087 100644
--- a/core/core.services.yml
+++ b/core/core.services.yml
@@ -154,7 +154,7 @@ services:
     class: Drupal\Core\Http\Plugin\SimpletestHttpRequestSubscriber
   http_default_client:
     class: Guzzle\Http\Client
-    arguments: [null, { curl.CURLOPT_TIMEOUT: 30, curl.CURLOPT_MAXREDIRS: 3 }]
+    arguments: [null, { curl.CURLOPT_TIMEOUT: 30, curl.CURLOPT_MAXREDIRS: 3, ssl.certificate_authority: system }]
     calls:
       - [addSubscriber, ['@http_client_simpletest_subscriber']]
       - [setUserAgent, ['Drupal (+http://drupal.org/)']]