diff --git a/tox.ini b/tox.ini
index 678e9db..c2fc078 100644
--- a/tox.ini
+++ b/tox.ini
@@ -4,7 +4,7 @@
 ignore_basepython_conflict = True
 
 [testenv]
-basepython = python3
+basepython = {env:TOX_PYTHON:python3}
 usedevelop = True
 setenv =
    VIRTUAL_ENV={envdir}
@@ -14,6 +14,7 @@
    OS_STDERR_CAPTURE={env:OS_STDERR_CAPTURE:true}
 deps =
   -c{env:TOX_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/master}
+  -r{toxinidir}/requirements.txt
   -r{toxinidir}/test-requirements.txt
 commands = stestr run --slowest {posargs}