Build the extension before testing
diff --git a/.travis.yml b/.travis.yml
index 55a9dba..ac0c065 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -9,4 +9,6 @@
 # command to run tests, e.g. python setup.py test
 install: pip install -r requirements.txt
 
+before_script: python setup.py build_ext
+
 script: python setup.py test