diff --git a/.travis.yml b/.travis.yml
index 0e038f4c..9ff7252d 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -14,10 +14,14 @@ matrix:
         - python: 2.7
           env:
             - PYTHON=python
+            - PYTHONWARNINGS=all
+            - PYTHONX=python
             - PYVER=2.x
         - python: 3.2
           env:
             - PYTHON=python3
+            - PYTHONWARNINGS=all
+            - PYTHONX=python3
             - PYVER=3.x
     exclude:
         - python: 2.6
@@ -71,8 +75,8 @@ script:
     - fi
     # Run all doc examples
     - export PYTHONPATH=$(pwd):$PYTHONPATH
-    - for f in doc/examples/*.py; do $PYTHON "$f"; if [ $? -ne 0 ]; then exit 1; fi done
-    - for f in doc/examples/applications/*.py; do $PYTHON "$f"; if [ $? -ne 0 ]; then exit 1; fi done
+    - for f in doc/examples/*.py; do $PYTHONX "$f"; if [ $? -ne 0 ]; then exit 1; fi done
+    - for f in doc/examples/applications/*.py; do $PYTHONX "$f"; if [ $? -ne 0 ]; then exit 1; fi done
 
     # Run pep8 and flake tests
     - flake8 --exit-zero --exclude=test_*,six.py skimage doc/examples viewer_examples