diff --git a/tox.ini b/tox.ini
index ff09b3f..cf41586 100644
--- a/tox.ini
+++ b/tox.ini
@@ -1,11 +1,14 @@
 [tox]
 envlist = pep8
+minversion = 1.6
+skipsdist = True
 
 [testenv]
 setenv = VIRTUAL_ENV={envdir}
          LANG=en_US.UTF-8
          LANGUAGE=en_US:en
          LC_ALL=C
+usedevelop = True
 
 [testenv:all]
 sitepackages = True
@@ -15,7 +18,6 @@
 
 [testenv:full]
 sitepackages = True
-setenv = VIRTUAL_ENV={envdir}
 # The regex below is used to select which tests to run and exclude the slow tag:
 # See the testrepostiory bug: https://bugs.launchpad.net/testrepository/+bug/1208610
 commands =
@@ -23,21 +25,18 @@
 
 [testenv:testr-full]
 sitepackages = True
-setenv = VIRTUAL_ENV={envdir}
 commands =
   sh tools/pretty_tox.sh '(?!.*\[.*\bslow\b.*\])(^tempest\.(api|scenario|thirdparty|cli|tests)) {posargs}'
 
 [testenv:heat-slow]
 sitepackages = True
-setenv = VIRTUAL_ENV={envdir}
-         OS_TEST_TIMEOUT=1200
+setenv = OS_TEST_TIMEOUT=1200
 # The regex below is used to select heat api/scenario tests tagged as slow.
 commands =
   sh tools/pretty_tox_serial.sh '(?=.*\[.*\bslow\b.*\])(^tempest\.(api|scenario)\.orchestration) {posargs}'
 
 [testenv:large-ops]
 sitepackages = True
-setenv = VIRTUAL_ENV={envdir}
 commands =
   python setup.py testr --slowest --testr-args='tempest.scenario.test_large_ops {posargs}'
 
@@ -69,7 +68,6 @@
 
 [testenv:smoke]
 sitepackages = True
-setenv = VIRTUAL_ENV={envdir}
 # This is still serial because neutron doesn't work with parallel. See:
 # https://bugs.launchpad.net/tempest/+bug/1216076 so the neutron smoke
 # job would fail if we moved it to parallel.
@@ -78,7 +76,6 @@
 
 [testenv:coverage]
 sitepackages = True
-setenv = VIRTUAL_ENV={envdir}
 commands =
    python -m tools/tempest_coverage -c start --combine
    sh tools/pretty_tox.sh '(?!.*\[.*\bslow\b.*\])(^tempest\.(api|scenario|thirdparty|cli|tests))'
@@ -86,7 +83,6 @@
 
 [testenv:stress]
 sitepackages = True
-setenv = VIRTUAL_ENV={envdir}
 commands =
     python -m tempest/stress/run_stress -a -d 3600 -S