diff --git a/.github/workflows/pythonpackage.yml b/.github/workflows/pythonpackage.yml
index 8efae9e..4687022 100644
--- a/.github/workflows/pythonpackage.yml
+++ b/.github/workflows/pythonpackage.yml
@@ -12,7 +12,7 @@
       matrix:
         python-version: ['3.11', '3.13']
         r-version: [release]
-        os: [macOS-latest, ubuntu-latest]
+        os: [macos-15, ubuntu-latest]
     steps:
     - uses: actions/checkout@v4
     - name: Set up Python ${{ matrix.python-version }}
@@ -26,7 +26,19 @@
         r-version: ${{ matrix.r-version }}
         use-public-rspm: true
         cache-version: 2
+    - name: Set env commands (POSIX)
+      if: "!startsWith(matrix.os, 'windows')"
+      run: |
+          echo "VENV_ACTIVATE=source pyenv_base/bin/activate" >> $GITHUB_ENV
+          echo "R_LIBRARY=export LD_LIBRARY_PATH=$(python -m rpy2.situation LD_LIBRARY_PATH):${LD_LIBRARY_PATH}" >> $GITHUB_ENV
+    - name: Set virtualenv activation command (Windows)
+      if: startsWith(matrix.os, 'windows')
+      shell: bash
+      run: |
+          echo "VENV_ACTIVATE=pyenv_base\Scripts\activate" >> $GITHUB_ENV
+          echo "R_LIBRARY=''" >> $GITHUB_ENV
     - name: Patch GHA issue with macos - Missing C library
+      if: startsWith(matrix.os, 'macos')
       shell: bash
       run: |
         LIB_ARCHIVES=(\
@@ -38,7 +50,10 @@
             curl -LO https://mac.r-project.org/bin/darwin20/arm64/"${name}"
             sudo tar xJf "${name}" -C /
         done
-      if: runner.os == 'macOS'
+    - name: Install dependencies
+      run: |
+        python -m pip install --upgrade pip
+        python -m pip install setuptools build
     - name: Set up package maintainers R on Linux
       run: |
         sudo apt-get update -y
@@ -63,11 +78,13 @@
         path: ${{ env.R_LIBS_USER }}
         key: ${{ runner.os }}-r-${{ matrix.config.r-version }}-${{ hashFiles('DESCRIPTION') }}
       if: runner.os != 'Linux'
-    - name: Install dependencies
-      run: |
-        python -m pip install --upgrade pip
-        pip install deflate wheel
     - name: Install package
+      if: runner.os != 'Windows'
+      run: |
+        pip install rpy2
+        pip install .
+    - name: Install package on Windows
+      if: runner.os == 'Windows'
       run: |
         pip install rpy2
         pip install .