diff --git a/.github/workflows/update-index.yaml b/.github/workflows/update-index.yaml
index abcee3e..317d8b8 100644
--- a/.github/workflows/update-index.yaml
+++ b/.github/workflows/update-index.yaml
@@ -111,7 +111,7 @@ jobs:
       - name: Set up Python for candidate validation
         uses: actions/setup-python@v7
         with:
-          python-version: '3.12'
+          python-version: '3.15'
 
       - name: Install candidate validation dependencies
         run: |
diff --git a/.github/workflows/validate-charts.yaml b/.github/workflows/validate-charts.yaml
index 46024f6..01cd42a 100644
--- a/.github/workflows/validate-charts.yaml
+++ b/.github/workflows/validate-charts.yaml
@@ -13,7 +13,7 @@ permissions:
 
 # Tool versions for both CI and the local checks in CONTRIBUTING.md.
 env:
-  PYTHON_VERSION: '3.12'
+  PYTHON_VERSION: '3.15'
   HELM_VERSION: 'v3.22.1'
 
 jobs:
diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index 782eac1..7a670f3 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -13,7 +13,7 @@ the Ubuntu runner supplies `sh`, `jq`, and `sha256sum`.
 From the repository root, create an isolated Python environment and run:
 
 ```sh
-python3.12 -m venv .venv
+python3.15 -m venv .venv
 .venv/bin/python -m pip install -r requirements-dev.txt
 .venv/bin/python -m unittest discover -s tests -v
 for chart in charts/*/Chart.yaml; do