diff --git a/.travis.yml b/.travis.yml
index f638339..9129f83 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -44,7 +44,7 @@ install:
   
 script:
   - mkdir -p build/logs
-  - vendor/bin/phpunit tests --coverage-clover build/logs/clover.xml
+  - XDEBUG_MODE=coverage vendor/bin/phpunit tests --coverage-clover build/logs/clover.xml
 
 after_success:
   - travis_retry php vendor/bin/php-coveralls -v