diff --git a/.github/workflows/docs.yml b/.github/workflows/docs.yml
index 9975a632bf..7c2b670b22 100644
--- a/.github/workflows/docs.yml
+++ b/.github/workflows/docs.yml
@@ -37,4 +37,6 @@ jobs:
       - name: Build docs
         run: |
           cd docs
-          sphinx-build -b spelling -n -q -W --keep-going -d _build/doctrees -D language=en_US -j auto . _build/spelling
+          export SPHINXOPTS="-q -W --keep-going -j auto"
+          export LANGUAGE=en_US
+          make spelling
diff --git a/docs/Makefile b/docs/Makefile
index 2b44830531..f175f89d51 100644
--- a/docs/Makefile
+++ b/docs/Makefile
@@ -14,14 +14,10 @@ ifndef LANGUAGE
 override LANGUAGE = en
 endif
 
-# Convert something like "en_US" to "en", because Sphinx does not recognize
-# underscores. Country codes should be passed using a dash, e.g. "pt-BR".
-LANGUAGEOPT = $(firstword $(subst _, ,$(LANGUAGE)))
-
 # Internal variables.
 PAPEROPT_a4     = -D latex_paper_size=a4
 PAPEROPT_letter = -D latex_paper_size=letter
-ALLSPHINXOPTS   = -n -d $(BUILDDIR)/doctrees -D language=$(LANGUAGEOPT) $(PAPEROPT_$(PAPER)) $(SPHINXOPTS) .
+ALLSPHINXOPTS   = -n -d $(BUILDDIR)/doctrees -D language=$(LANGUAGE) $(PAPEROPT_$(PAPER)) $(SPHINXOPTS) .
 # the i18n builder cannot share the environment and doctrees with the others
 I18NSPHINXOPTS  = $(PAPEROPT_$(PAPER)) $(SPHINXOPTS) .
 
diff --git a/docs/spelling_wordlist b/docs/spelling_wordlist
index 0b9180fd35..2869b4d361 100644
--- a/docs/spelling_wordlist
+++ b/docs/spelling_wordlist
@@ -149,6 +149,7 @@ drilldown
 dropdown
 dropdowns
 Dunck
+dz
 editability
 encodings
 Endian
@@ -250,6 +251,7 @@ Kyngesburye
 Kyrgyz
 latin
 lawrence
+lexer
 Libera
 lifecycle
 lifecycles
@@ -349,6 +351,7 @@ pingback
 pingbacks
 Pinney
 Pinterest
+pk
 plaintext
 pluggable
 pluralizations
@@ -410,6 +413,7 @@ recomputation
 recursed
 redeclare
 redirections
+Redis
 redisplay
 redisplayed
 redisplaying
@@ -458,6 +462,7 @@ shapefiles
 sharding
 sitewide
 sliceable
+Slocum
 SMTP
 solaris
 Sorani
@@ -465,6 +470,7 @@ sortable
 Spectre
 Springmeyer
 SSL
+st
 stacktrace
 stateful
 staticfile
diff --git a/tox.ini b/tox.ini
index 3b9f663385..cd088eadda 100644
--- a/tox.ini
+++ b/tox.ini
@@ -56,6 +56,9 @@ deps =
     pyenchant
     sphinxcontrib-spelling
 changedir = docs
+setenv =
+    SPHINXOPTS=-W --keep-going -j auto
+    LANGUAGE=en_US
 commands =
     make spelling