diff --git a/tests/conftest.py b/tests/conftest.py
index 336484bcc..0d6b39681 100644
--- a/tests/conftest.py
+++ b/tests/conftest.py
@@ -40,9 +40,7 @@ def _filter_warnings():
 
     ignore(category=DeprecationWarning, module='site')  # virtualenv
     ignore(category=PendingDeprecationWarning, module=r'_pytest\..*')
-    ignore(category=ImportWarning, module='backports')
     ignore(category=ImportWarning, module='pkgutil')
-    ignore(category=ImportWarning, module='pytest_cov')
 
 
 def _initialize_test_directory(session):
diff --git a/tox.ini b/tox.ini
index 0d19225f8..99e243ad6 100644
--- a/tox.ini
+++ b/tox.ini
@@ -20,6 +20,7 @@ deps =
     du13: docutils==0.13.1
     du14: docutils==0.14
 setenv =
+    PYTHONWARNINGS = all,ignore::ImportWarning:pkgutil
     SPHINX_TEST_TEMPDIR = {envdir}/testbuild
 commands=
     pytest -Wall --durations 25 {posargs}