diff --git a/tox.ini b/tox.ini
index 57811fa80f63..03712efc51c1 100644
--- a/tox.ini
+++ b/tox.ini
@@ -27,14 +27,14 @@ passenv = OS_DEBUG GENERATE_HASHES
 [testenv:py27]
 commands =
     {[testenv]commands}
-    stestr run '{posargs}'
+    stestr run {posargs}
     env TEST_OSPROFILER=1 stestr run --combine --no-discover 'nova.tests.unit.test_profiler'
     stestr slowest
 
 [testenv:py35]
 commands =
     {[testenv]commands}
-    stestr run --blacklist-file=tests-py3.txt '{posargs}'
+    stestr run --blacklist-file=tests-py3.txt {posargs}
     env TEST_OSPROFILER=1 stestr run --combine --no-discover 'nova.tests.unit.test_profiler'
 
 [testenv:py36]
@@ -78,7 +78,7 @@ commands =
 # special way. See the following for more details.
 # http://stestr.readthedocs.io/en/latest/MANUAL.html#grouping-tests
 # https://gabbi.readthedocs.io/en/latest/#purpose
-  stestr --test-path=./nova/tests/functional --group-regex=nova\.tests\.functional\.api\.openstack\.placement\.test_placement_api(?:\.|_)([^_]+) run '{posargs}'
+  stestr --test-path=./nova/tests/functional --group_regex=nova\.tests\.functional\.api\.openstack\.placement\.test_placement_api(?:\.|_)([^_]+) run {posargs}
   stestr slowest
 
 # TODO(gcb) Merge this into [testenv:functional] when functional tests are gating
@@ -97,7 +97,7 @@ commands =
 # special way. See the following for more details.
 # http://stestr.readthedocs.io/en/latest/MANUAL.html#grouping-tests
 # https://gabbi.readthedocs.io/en/latest/#purpose
-    stestr --test-path=./nova/tests/functional --group-regex=nova\.tests\.functional\.api\.openstack\.placement\.test_placement_api(?:\.|_)([^_]+) run '{posargs}'
+    stestr --test-path=./nova/tests/functional --group_regex=nova\.tests\.functional\.api\.openstack\.placement\.test_placement_api(?:\.|_)([^_]+) run {posargs}
 
 [testenv:api-samples]
 usedevelop = True
@@ -106,7 +106,7 @@ setenv = {[testenv]setenv}
          PYTHONHASHSEED=0
 commands =
   find . -type f -name "*.pyc" -delete
-  stestr --test-path=./nova/tests/functional/api_sample_tests run '{posargs}'
+  stestr --test-path=./nova/tests/functional/api_sample_tests run {posargs}
   stestr slowest
 
 [testenv:genconfig]
@@ -123,7 +123,7 @@ setenv = {[testenv]setenv}
 commands =
   coverage erase
   find . -type f -name "*.pyc" -delete
-  stestr run '{posargs}'
+  stestr run {posargs}
   coverage combine
   coverage html -d cover
   coverage xml -o cover/coverage.xml