diff --git a/.travis.yml b/.travis.yml
index f1293bd..e641b80 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -8,6 +8,7 @@ php:
 
 install:
   - if [[ $TRAVIS_PHP_VERSION = '5.6' ]]; then composer require satooshi/php-coveralls:~0.6@stable ; fi
+  - if [[ $TRAVIS_PHP_VERSION = '5.6' ]]; then composer require symfony/yaml:2.4.* ; fi
 
 before_script:
   - if [[ $TRAVIS_PHP_VERSION = '5.6' ]]; then PHPUNIT_FLAGS="--coverage-clover ./build/logs/clover.xml"; else PHPUNIT_FLAGS=""; fi