diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index 2257bad8d618..4519c18019e9 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -20,6 +20,12 @@ jobs:
         with:
           python-version-file: .python-version
           allow-prereleases: true
+      # keras needs hdf5 on pre-release Python.
+      - run: |
+          if [ "$(python -c 'import sys; print(sys.version_info.releaselevel)')" != "final" ]; then
+            sudo apt-get update -qq
+            sudo apt-get install --yes libhdf5-dev
+          fi
       - run: uv sync --group=test
       - name: Run tests
         # opencv-python is gated out on 3.14t (no cp314t wheel yet), so skip the
diff --git a/.github/workflows/sphinx.yml b/.github/workflows/sphinx.yml
index 1672bf69407f..905e0c1ebee3 100644
--- a/.github/workflows/sphinx.yml
+++ b/.github/workflows/sphinx.yml
@@ -33,6 +33,12 @@ jobs:
         with:
           python-version-file: .python-version
           allow-prereleases: true
+      # keras needs hdf5 on pre-release Python.
+      - run: |
+          if [ "$(python -c 'import sys; print(sys.version_info.releaselevel)')" != "final" ]; then
+            sudo apt-get update -qq
+            sudo apt-get install --yes libhdf5-dev
+          fi
       - run: uv sync --group=docs
       - uses: actions/configure-pages@v6
       - run: uv run sphinx-build -c docs . docs/_build/html
diff --git a/pyproject.toml b/pyproject.toml
index 3d0dbdd05018..a8d37abac664 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -23,7 +23,7 @@ dependencies = [
   "pandas>=2.3.3",
   "pillow>=11.3",
   "rich>=13.9.4",
-  "scikit-learn>=1.9",
+  "scikit-learn>=1.9.1",
   "scipy>=1.18.1",
   "statsmodels>=0.14.4",
   "sympy>=1.13.3",