diff --git a/docs/requirements.txt b/docs/requirements.txt
deleted file mode 100644
index 483a4e96..00000000
--- a/docs/requirements.txt
+++ /dev/null
@@ -1 +0,0 @@
-sphinx_rtd_theme
diff --git a/docs/source/conf.py b/docs/source/conf.py
index 2590f326..15847741 100644
--- a/docs/source/conf.py
+++ b/docs/source/conf.py
@@ -90,7 +90,7 @@ todo_include_todos = True
 # The theme to use for HTML and HTML Help pages.  See the documentation for
 # a list of builtin themes.
 #
-html_theme = 'sphinx_rtd_theme'
+html_theme = 'alabaster'
 
 # Theme options are theme-specific and customize the look and feel of a theme
 # further.  For a list of options available for each theme, see the
diff --git a/environment.yml b/environment.yml
index 77489382..3e7c5b28 100644
--- a/environment.yml
+++ b/environment.yml
@@ -2,7 +2,7 @@ name: py_test
 channels:
   - anaconda
 dependencies:
-  - python>=3.5
+  - python==3.6
   - pip
   - openssl
   - xz
@@ -29,4 +29,3 @@ dependencies:
   - six
   - snowballstemmer
   - sphinx
-  - sphinx_rtd_theme