diff --git a/.travis.yml b/.travis.yml
index 8df2e2d..daeae07 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -20,5 +20,6 @@ before_script:
   - export DISPLAY=:99.0
   - sh -e /etc/init.d/xvfb start
   - sleep 3 # give xvfb some time to start
+  - rm -rf 12 13 14 15 16 17 18 # ugly ...
 script:
   - make && [ -e book.pdf ]