diff --git a/tox.ini b/tox.ini
index d673497e..cd215054 100644
--- a/tox.ini
+++ b/tox.ini
@@ -10,14 +10,14 @@ commands=
 
 [testenv:coveralls]
 basepython=python3.5
-passenv=TRAVIS TRAVIS_JOB_ID TRAVIS_BRANCH
+passenv=TRAVIS TRAVIS_JOB_ID TRAVIS_BRANCH DEPENDENCY_INJECTOR_DEBUG_MODE
 deps=
     {[testenv]deps}
     cython
     coverage
     coveralls
 commands=
-    {envpython} setup.py install
+    {envpython} setup.py build_ext --inplace
     coverage erase
     coverage run --rcfile=./.coveragerc -m unittest2 discover tests
     coveralls