diff --git a/.travis.yml b/.travis.yml
index fcb6d94e..7fdb729d 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -13,7 +13,7 @@ matrix:
 before_script:
   ## Composer
   - curl -s http://getcomposer.org/installer | php
-  - php composer.phar install
+  - php composer.phar install --prefer-source
   ## PHP_CodeSniffer
   - pyrus install pear/PHP_CodeSniffer
   - phpenv rehash