diff --git a/wp-includes/class-http.php b/wp-includes/class-http.php
index e9ff205142..d3a893787c 100644
--- a/wp-includes/class-http.php
+++ b/wp-includes/class-http.php
@@ -356,6 +356,7 @@ class WP_Http {
 			$options['proxy'] = new Requests_Proxy_HTTP( $proxy->host() . ':' . $proxy->port() );
 
 			if ( $proxy->use_authentication() ) {
+				$options['proxy']->use_authentication = true;
 				$options['proxy']->user = $proxy->username();
 				$options['proxy']->pass = $proxy->password();
 			}
diff --git a/wp-includes/version.php b/wp-includes/version.php
index 9a0d9b849b..8ebe91a686 100644
--- a/wp-includes/version.php
+++ b/wp-includes/version.php
@@ -4,7 +4,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '4.6-RC1-38172';
+$wp_version = '4.6-RC1-38173';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.