diff --git a/.github/workflows/ci.yaml b/.github/workflows/ci.yaml
index 0d5a5309..0e096030 100644
--- a/.github/workflows/ci.yaml
+++ b/.github/workflows/ci.yaml
@@ -18,7 +18,7 @@ jobs:
       - uses: actions/checkout@v3
       - uses: actions/setup-python@v4
         with:
-          python-version: "3.12"
+          python-version: "3.13"
       - run: pip install -r requirements.txt
       - run: pre-commit run --all-files
       - run: mypy kopf --strict
@@ -38,10 +38,10 @@ jobs:
       fail-fast: false
       matrix:
         install-extras: [ "", "full-auth" ]
-        python-version: [ "3.8", "3.9", "3.10", "3.11", "3.12" ]
+        python-version: [ "3.8", "3.9", "3.10", "3.11", "3.12", "3.13" ]
         include:
           - install-extras: "uvloop"
-            python-version: "3.12"
+            python-version: "3.13"
     name: Python ${{ matrix.python-version }} ${{ matrix.install-extras }}
     runs-on: ubuntu-22.04
     timeout-minutes: 5  # usually 2-3 mins
diff --git a/kopf/_core/engines/posting.py b/kopf/_core/engines/posting.py
index 3c83954d..1aaa4443 100644
--- a/kopf/_core/engines/posting.py
+++ b/kopf/_core/engines/posting.py
@@ -183,11 +183,13 @@ class K8sPoster(logging.Handler):
     """
     A handler to post all log messages as K8s events.
     """
-
-    def createLock(self) -> None:
-        # Save some time on unneeded locks. Events are posted in the background.
-        # We only put events to the queue, which is already lock-protected.
-        self.lock = None
+    if sys.version_info[:2] < (3, 13):
+        # Disable this optimisation for Python >= 3.13.
+        # The `handle` no longer support having `None` as lock.
+        def createLock(self) -> None:
+            # Save some time on unneeded locks. Events are posted in the background.
+            # We only put events to the queue, which is already lock-protected.
+            self.lock = None
 
     def filter(self, record: logging.LogRecord) -> bool:
         # Only those which have a k8s object referred (see: `ObjectLogger`).
diff --git a/requirements.txt b/requirements.txt
index a9b0b6ad..88ee4ebe 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -21,5 +21,5 @@ pytest-asyncio
 pytest-cov
 pytest-mock
 pytest-timeout
-types-setuptools
 types-PyYAML
+types-setuptools
diff --git a/setup.py b/setup.py
index 4beebb1c..822892a6 100644
--- a/setup.py
+++ b/setup.py
@@ -38,6 +38,7 @@
         'Programming Language :: Python :: 3.10',
         'Programming Language :: Python :: 3.11',
         'Programming Language :: Python :: 3.12',
+        'Programming Language :: Python :: 3.13',
         'Programming Language :: Python :: 3 :: Only',
         'Programming Language :: Python :: Implementation :: CPython',
         'Programming Language :: Python :: Implementation :: PyPy',