diff --git a/Dockerfile b/Dockerfile
index 822c1ce..f16ed40 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,6 +1,6 @@
 # Base image pinned by its multi-arch index digest, so a re-pushed tag cannot
 # change what is built. Refresh the digest and the tag together.
-FROM python:3.11.16-slim-bookworm@sha256:a36c24f9cbdf4fd0f52d67f0823eeac19c2028c637cecc392d97f980d4fec56b AS builder
+FROM python:3.11.17-slim-bookworm@sha256:2333bd330d12de02514770b3585cad313644316047cdee24a7acfdece6de6efb AS builder
 
 ENV PIP_DISABLE_PIP_VERSION_CHECK=1 \
     PIP_NO_CACHE_DIR=1
@@ -14,7 +14,7 @@ COPY pyproject.toml README.md LICENSE NOTICE ./
 COPY src ./src
 RUN python -m pip wheel --no-deps --no-build-isolation --wheel-dir /wheels .
 
-FROM python:3.11.16-slim-bookworm@sha256:a36c24f9cbdf4fd0f52d67f0823eeac19c2028c637cecc392d97f980d4fec56b AS runtime
+FROM python:3.11.17-slim-bookworm@sha256:2333bd330d12de02514770b3585cad313644316047cdee24a7acfdece6de6efb AS runtime
 
 ENV PIP_DISABLE_PIP_VERSION_CHECK=1 \
     PIP_NO_CACHE_DIR=1 \
diff --git a/tests/unit/test_container_release.py b/tests/unit/test_container_release.py
index 257fac8..728ffb7 100644
--- a/tests/unit/test_container_release.py
+++ b/tests/unit/test_container_release.py
@@ -11,8 +11,11 @@
 
 def test_runtime_image_is_multistage_non_root_and_offline_installed() -> None:
     dockerfile = Path("Dockerfile").read_text(encoding="utf-8")
-    # Both stages pin the base image by digest, not by tag alone.
-    assert dockerfile.count("FROM python:3.11.16-slim-bookworm@sha256:") == 2
+    # Both stages pin the base image by patch release and digest, not by tag alone.
+    base_stages = re.findall(
+        r"^FROM python:3\.11\.\d+-slim-bookworm@sha256:[0-9a-f]{64} AS ", dockerfile, re.M
+    )
+    assert len(base_stages) == 2
     assert "AS builder" in dockerfile
     assert "pip install --require-hashes -r requirements/build.txt" in dockerfile
     assert "pip wheel --no-deps --no-build-isolation --wheel-dir /wheels ." in dockerfile