diff --git a/.travis.yml b/.travis.yml
index cbf4eee7dd..75568167b3 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -183,7 +183,7 @@ before_install:
               tfold ext.redis tpecl redis-5.2.2 redis.so $INI "no"
           fi
 
-          tfold ext.igbinary tpecl igbinary-3.1.2 igbinary.so $INI
+          tfold ext.igbinary tpecl igbinary-3.1.5 igbinary.so $INI
       done
     - |
       # List all php extensions with versions
diff --git a/src/Symfony/Component/HttpClient/NativeHttpClient.php b/src/Symfony/Component/HttpClient/NativeHttpClient.php
index c0d49bcfd6..f74e621bb8 100644
--- a/src/Symfony/Component/HttpClient/NativeHttpClient.php
+++ b/src/Symfony/Component/HttpClient/NativeHttpClient.php
@@ -214,7 +214,7 @@ final class NativeHttpClient implements HttpClientInterface, LoggerAwareInterfac
                 'disable_compression' => true,
             ], static function ($v) { return null !== $v; }),
             'socket' => [
-                'bindto' => $options['bindto'],
+                'bindto' => $options['bindto'] ?: '0:0',
                 'tcp_nodelay' => true,
             ],
         ];