diff --git a/docs/conf.py b/docs/conf.py
index 6f1ccba..f2225c5 100644
--- a/docs/conf.py
+++ b/docs/conf.py
@@ -67,7 +67,7 @@
 
 # Monkey patch to disable nonlocal image warning
 import sphinx
-if hasattr(sphinx, 'environment'):
+try:
     original_warn_mode = sphinx.environment.BuildEnvironment.warn_node
 
     def allow_nonlocal_image_warn_node(self, msg, *args, **kwargs):
@@ -76,6 +76,8 @@ def allow_nonlocal_image_warn_node(self, msg, *args, **kwargs):
 
     sphinx.environment.BuildEnvironment.warn_node = \
         allow_nonlocal_image_warn_node
+except AttributeError:
+    pass
 
 suppress_warnings = [
     'image.nonlocal_uri',
diff --git a/tox.ini b/tox.ini
index 33b165c..b588f0a 100644
--- a/tox.ini
+++ b/tox.ini
@@ -19,7 +19,7 @@ deps = flake8
 commands = flake8 --ignore=W391 python_utils {posargs}
 
 [testenv:docs]
-basepython = python2.7
+basepython = python3
 whitelist_externals =
     rm
     cd