diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index a9ffb0d2..1da80ba9 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -16,7 +16,7 @@ jobs:
         with:
           poetry-version: '1.1.12'
       - run: pip install tox
-      - run: tox -e lint,py310-dj32
+      - run: tox -e lint,py310-dj40
   test_compatibility:
     needs: test
     runs-on: ubuntu-latest
@@ -29,10 +29,11 @@ jobs:
           - python: "3.7"
             toxenv: py37-dj22,py37-dj30,py37-dj31,py37-dj32
           - python: "3.8"
-            toxenv: py38-dj22,py38-dj30,py38-dj31,py38-dj32
+            toxenv: py38-dj22,py38-dj30,py38-dj31,py38-dj32,py38-dj40
           - python: "3.9"
-            toxenv: py39-dj22,py39-dj30,py39-dj31,py39-dj32
+            toxenv: py39-dj22,py39-dj30,py39-dj31,py39-dj32,py39-dj40
           - python: "3.10"
+            # Skip testing Django 4.0, already tested in previous workflow job.
             toxenv: py310-dj32,py310-djmain
     steps:
       - uses: actions/checkout@v2
diff --git a/pyproject.toml b/pyproject.toml
index c42d69e1..49bbd30a 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -25,6 +25,7 @@ classifiers = [
     "Framework :: Django :: 3.0",
     "Framework :: Django :: 3.1",
     "Framework :: Django :: 3.2",
+    "Framework :: Django :: 4.0",
 ]
 packages = [
     { include = "pattern_library" },
@@ -38,7 +39,7 @@ exclude = [
 
 [tool.poetry.dependencies]
 python = "^3.7"
-Django = ">=2.2,<4.0"
+Django = ">=2.2,<4.1"
 PyYAML = ">=5.1,<7.0"
 Markdown = "^3.1"
 
diff --git a/tox.ini b/tox.ini
index 63ffd8b9..fdd51691 100644
--- a/tox.ini
+++ b/tox.ini
@@ -1,5 +1,5 @@
 [tox]
-envlist = py{37,38,39,310}-dj{22,30,31,32,main}, lint
+envlist = py{37,38,39,310}-dj{22,30,31,32,40,main}, lint
 skipsdist = true
 
 [testenv]
@@ -15,6 +15,7 @@ deps =
     dj30: Django>=3.0,<3.1
     dj31: Django>=3.1,<3.2
     dj32: Django>=3.2,<3.3
+    dj40: Django>=4.0,<4.1
     djmain: https://github.com/django/django/archive/main.zip
 
 [testenv:lint]