diff --git a/tox.ini b/tox.ini
index e075386..d4ab42c 100644
--- a/tox.ini
+++ b/tox.ini
@@ -11,7 +11,7 @@ deps =
   taxii2-client
   medallion
 commands =
-  pytest --cov=stix2 stix2/test/ --cov-report term-missing -W ignore::stix2.exceptions.STIXDeprecationWarning
+  python -m pytest --cov=stix2 stix2/test/ --cov-report term-missing -W ignore::stix2.exceptions.STIXDeprecationWarning
 
 passenv = CI TRAVIS TRAVIS_*