diff --git a/.travis.yml b/.travis.yml
index e908dc2..6161d58 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -7,4 +7,4 @@ php:
 
 before_script:
   - curl -s http://getcomposer.org/installer | php
-  - php composer.phar install --dev
+  - php composer.phar install --dev --prefer-source