diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index 60a6c10..5cdf79b 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -14,8 +14,8 @@ jobs:
     runs-on: ${{ matrix.os }}
     strategy:
       matrix:
-        os: [macos-latest]
-        python: ["3.10", "3.11", "3.12"]
+        os: [macos-latest, windows-latest]
+        python: ["3.9", "3.10", "3.11", "3.12"]
 
     steps:
       - uses: compas-dev/compas-actions.build@v4
diff --git a/env_win.yml b/env_win.yml
index b95fe67..0aabfec 100644
--- a/env_win.yml
+++ b/env_win.yml
@@ -2,16 +2,16 @@ name: cgal-dev
 channels:
   - conda-forge
 dependencies:
-  - python>=3.9
-  - pip>=19.0
+  - python >=3.9
+  - pip >=19.0
   - mpir
   - mpfr
-  - scip
+  - scip >=9
   - boost-cpp
-  - eigen=3.3
+  - eigen =3.3
   - cgal-cpp
   - pybind11
-  - compas>=2.4
+  - compas >=2.4
   - pytest
   - pip:
       - .[DEV]