diff --git a/.travis.yml b/.travis.yml
index 08b8f9c..6427c0f 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -34,6 +34,7 @@ before_install:
 
 install:
     - composer require symfony/symfony:${SYMFONY_VERSION} --no-update
+    - composer require "php-http/guzzle6-adapter:^1.0" --no-update
     - composer install --prefer-source
 
 script: