diff --git a/docs/Makefile b/docs/Makefile
index 51285967..d4bb2cbb 100644
--- a/docs/Makefile
+++ b/docs/Makefile
@@ -1,9 +1,10 @@
 # Minimal makefile for Sphinx documentation
 #
 
-# You can set these variables from the command line.
-SPHINXOPTS    =
-SPHINXBUILD   = sphinx-build
+# You can set these variables from the command line, and also
+# from the environment for the first two.
+SPHINXOPTS    ?=
+SPHINXBUILD   ?= sphinx-build
 SOURCEDIR     = .
 BUILDDIR      = _build
 
diff --git a/docs/conf.py b/docs/conf.py
index 2bcda5af..39e56a8f 100644
--- a/docs/conf.py
+++ b/docs/conf.py
@@ -1,4 +1,4 @@
-import packaging
+import packaging.version
 from pallets_sphinx_themes import get_version
 from pallets_sphinx_themes import ProjectLink
 
diff --git a/docs/make.bat b/docs/make.bat
index 7893348a..922152e9 100644
--- a/docs/make.bat
+++ b/docs/make.bat
@@ -25,11 +25,11 @@ if errorlevel 9009 (
 	exit /b 1
 )
 
-%SPHINXBUILD% -M %1 %SOURCEDIR% %BUILDDIR% %SPHINXOPTS%
+%SPHINXBUILD% -M %1 %SOURCEDIR% %BUILDDIR% %SPHINXOPTS% %O%
 goto end
 
 :help
-%SPHINXBUILD% -M help %SOURCEDIR% %BUILDDIR% %SPHINXOPTS%
+%SPHINXBUILD% -M help %SOURCEDIR% %BUILDDIR% %SPHINXOPTS% %O%
 
 :end
 popd
diff --git a/docs/requirements.txt b/docs/requirements.txt
index 543ec917..b8e76e45 100644
--- a/docs/requirements.txt
+++ b/docs/requirements.txt
@@ -1,4 +1,5 @@
-Sphinx~=2.1.2
-Pallets-Sphinx-Themes~=1.1.4
-sphinxcontrib-log-cabinet~=1.0.0
+Sphinx~=2.2.0
+Pallets-Sphinx-Themes~=1.2.2
+sphinxcontrib-log-cabinet~=1.0.1
 sphinx-issues~=1.2.0
+packaging~=19.2