diff --git a/.travis.yml b/.travis.yml
index a2caf519..15a567f1 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -41,6 +41,8 @@ install:
       set +e
     fi
 - popd
+# pre-populate virtualenv separately from the actual testing (script step):
+- python -m tox.__main__ --notest
 
 before_script:
 - sudo ldconfig