diff --git a/appveyor.yml b/appveyor.yml
index 6dfdb45..ea2137b 100644
--- a/appveyor.yml
+++ b/appveyor.yml
@@ -7,6 +7,10 @@ environment:
       APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2019
       PYTHON: "C:\\Python39-x64"
 
+    - job_group: tests
+      APPVEYOR_BUILD_WORKER_IMAGE: Ubuntu2004
+      PYTHON: "3.10"
+
     - job_group: tests
       APPVEYOR_BUILD_WORKER_IMAGE: Ubuntu2004
       PYTHON: "3.9"
@@ -23,10 +27,14 @@ environment:
       APPVEYOR_BUILD_WORKER_IMAGE: Ubuntu2004
       PYTHON: "3.6"
 
+    - job_group: tests
+      APPVEYOR_BUILD_WORKER_IMAGE: macos
+      PYTHON: "3.9"
+
     - job_name: deploy
       job_depends_on: tests
       APPVEYOR_BUILD_WORKER_IMAGE: Ubuntu2004
-      PYTHON: "3.9"
+      PYTHON: "3.10"
 
   GIT_TOKEN:
     secure: +jQhxLpePj6hdDryfET/XpLo7VL9fhDXVHlwLOPp/nRDYe97TJAfd0XCTuPz1qkT
@@ -50,10 +58,12 @@ for:
       - cmd: 'echo %PATH%'
       # Shared config.
       - python -m pip install --upgrade pip setuptools nox
+      - python --version
     test_script:
       # GNU/Linux test.
       - sh: nox --non-interactive --error-on-missing-interpreters --session test lint --python $PYTHON
-      - sh: nox --non-interactive --session docs
+      # skip macOS docs build
+      - sh: 'if [ "$APPVEYOR_BUILD_WORKER_IMAGE" != "macos" ]; then nox --non-interactive --session docs; fi'
       # MS Windows test.
       - cmd: nox --forcecolor --non-interactive --error-on-missing-interpreters --session test lint
       # Shared test for all platforms.
diff --git a/docs/requirements.txt b/docs/requirements.txt
index b9cbbe7..3b0f1ff 100644
--- a/docs/requirements.txt
+++ b/docs/requirements.txt
@@ -1,3 +1,3 @@
-sphinx           == 3.5.3
-sphinx_rtd_theme == 0.5.1
+sphinx           == 4.3.1
+sphinx_rtd_theme == 1.0.0
 sphinx-computron >= 0.2, < 2.0
diff --git a/noxfile.py b/noxfile.py
index f291591..3d77d0a 100644
--- a/noxfile.py
+++ b/noxfile.py
@@ -9,7 +9,7 @@
 import nox
 
 
-PYTHONS = ["3.6", "3.7", "3.8", "3.9"]
+PYTHONS = ["3.6", "3.7", "3.8", "3.9", "3.10"]
 """The newest supported Python shall be listed LAST."""
 
 nox.options.error_on_external_run = True
@@ -84,7 +84,7 @@ def lint(session):
         },
     )
     if is_latest_python(session):
-        session.install("black == 20.8b1")
+        session.install("black == 21.4b2")
         session.run("black", "--check", ".")