diff --git a/tox.ini b/tox.ini
index 4f2465a..9c32121 100644
--- a/tox.ini
+++ b/tox.ini
@@ -6,23 +6,28 @@
 [testenv]
 setenv = VIRTUAL_ENV={envdir}
          OS_TEST_PATH=./tempest/test_discover
+         PYTHONHASHSEED=0
 usedevelop = True
 install_command = pip install -U {opts} {packages}
 
 [testenv:py26]
 setenv = OS_TEST_PATH=./tempest/tests
+         PYTHONHASHSEED=0
 commands = python setup.py test --slowest --testr-arg='tempest\.tests {posargs}'
 
 [testenv:py33]
 setenv = OS_TEST_PATH=./tempest/tests
+         PYTHONHASHSEED=0
 commands = python setup.py test --slowest --testr-arg='tempest\.tests {posargs}'
 
 [testenv:py27]
 setenv = OS_TEST_PATH=./tempest/tests
+         PYTHONHASHSEED=0
 commands = python setup.py test --slowest --testr-arg='tempest\.tests {posargs}'
 
 [testenv:cover]
 setenv = OS_TEST_PATH=./tempest/tests
+         PYTHONHASHSEED=0
 commands = python setup.py testr --coverage --testr-arg='tempest\.tests {posargs}'
 
 [testenv:all]