diff --git a/.travis.yml b/.travis.yml
index 23225dbbb..b5adc2da7 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -30,8 +30,10 @@ matrix:
     - python: '3.5'
     - python: '3.5'
       dist: trusty
+      env: PYTHONOPTIMIZE=1
     - python: '3.4'
       dist: trusty
+      env: PYTHONOPTIMIZE=2
     - env: DOCKER="alpine" DOCKER_TAG="pytest"
     - env: DOCKER="arch" DOCKER_TAG="pytest" # contains PyQt5
     - env: DOCKER="ubuntu-trusty-x86" DOCKER_TAG="pytest"