diff --git a/cinderclient/utils.py b/cinderclient/utils.py
index 0d8408e94..f9af58d30 100644
--- a/cinderclient/utils.py
+++ b/cinderclient/utils.py
@@ -187,7 +187,7 @@ def print_list(objs, fields, exclude_unavailable=False, formatters=None,
 
 def _encode(src):
     """remove extra 'u' in PY2."""
-    if six.PY2 and isinstance(src, unicode):
+    if six.PY2 and isinstance(src, six.text_type):
         return src.encode('utf-8')
     return src
 
diff --git a/tox.ini b/tox.ini
index f60267f59..c90c24e2c 100644
--- a/tox.ini
+++ b/tox.ini
@@ -24,9 +24,11 @@ commands = find . -type f -name "*.pyc" -delete
 whitelist_externals = find
 
 [testenv:pep8]
+basepython = python3
 commands = flake8
 
 [testenv:pylint]
+basepython = python3
 deps =
   -c{env:UPPER_CONSTRAINTS_FILE:https://git.openstack.org/cgit/openstack/requirements/plain/upper-constraints.txt}
   -r{toxinidir}/requirements.txt
@@ -35,9 +37,11 @@ commands = bash tools/lintstack.sh
 whitelist_externals = bash
 
 [testenv:venv]
+basepython = python3
 commands = {posargs}
 
 [testenv:cover]
+basepython = python3
 setenv =
     {[testenv]setenv}
     PYTHON=coverage run --source cinderclient --parallel-mode
@@ -48,6 +52,7 @@ commands =
     coverage xml -o cover/coverage.xml
 
 [testenv:docs]
+basepython = python3
 deps =
   -c{env:UPPER_CONSTRAINTS_FILE:https://git.openstack.org/cgit/openstack/requirements/plain/upper-constraints.txt}
   -r{toxinidir}/requirements.txt
@@ -55,6 +60,7 @@ deps =
 commands = sphinx-build -b html doc/source doc/build/html
 
 [testenv:releasenotes]
+basepython = python3
 deps =
   -c{env:UPPER_CONSTRAINTS_FILE:https://git.openstack.org/cgit/openstack/requirements/plain/upper-constraints.txt}
   -r{toxinidir}/requirements.txt
@@ -62,6 +68,7 @@ deps =
 commands = sphinx-build -a -E -W -d releasenotes/build/doctrees -b html releasenotes/source releasenotes/build/html
 
 [testenv:functional]
+basepython = python3
 commands = ostestr {posargs}
 setenv =
   {[testenv]setenv}