diff --git a/tox.ini b/tox.ini
index f6f399bbb2..c3c2688b0a 100644
--- a/tox.ini
+++ b/tox.ini
@@ -12,6 +12,9 @@ setenv = VIRTUAL_ENV={envdir}
          NOSE_OPENSTACK_RED=0.05
          NOSE_OPENSTACK_YELLOW=0.025
          NOSE_OPENSTACK_SHOW_ELAPSED=1
+# Note the hash seed is set to 0 until horizon can be tested with a
+# random hash seed successfully.
+         PYTHONHASHSEED=0
 deps = -r{toxinidir}/requirements.txt
        -r{toxinidir}/test-requirements.txt
 commands = /bin/bash run_tests.sh -N --no-pep8 {posargs}