diff -u b/includes/common.inc b/includes/common.inc
--- b/includes/common.inc
+++ b/includes/common.inc
@@ -877,12 +877,10 @@
       $options['headers']['Host'] = $uri['host'] . ($port != 443 ? ':' . $port : '');
       // By default, verify SSL certificates in OpenSSL connections. This is
       // enabled by default in PHP 5.6, older versions do not enable it
-      // automatically.
+      // automatically. Allow other SSL context options to be configured.
       if (!isset($options['context'])) {
         $opts = array(
-          'ssl' => array(
-            'verify_peer' => TRUE,
-          ),
+          'ssl' => variable_get('drupal_ssl_context_options', array('verify_peer' => TRUE))
         );
         $options['context'] = stream_context_create($opts);
       }