diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index 0816a9cd59..4c30ef6e4e 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -87,13 +87,29 @@ jobs:
         cmake --build ./build --target install
     - name: test
       run: python -m unittest discover -v ./Wrappers/Python/test
+  conda-matrix:
+    runs-on: ubuntu-latest
+    outputs:
+      python-version: ${{ steps.matrix.outputs.python-version }}
+      numpy-version: ${{ steps.matrix.outputs.numpy-version }}
+    steps:
+    - id: matrix
+      run: |
+        if ${{ github.ref == 'refs/heads/master' || startsWith(github.ref, 'refs/tags') }}; then
+          echo "python-version=['3.10', 3.11]" >> $GITHUB_OUTPUT
+          echo "numpy-version=[1.23, 1.24, 1.25, 1.26]" >> $GITHUB_OUTPUT
+        else
+          echo "python-version=['3.10']" >> $GITHUB_OUTPUT
+          echo "numpy-version=[1.23]" >> $GITHUB_OUTPUT
+        fi
   conda:
     defaults: {run: {shell: 'bash -el {0}'}}
     runs-on: ubuntu-latest
+    needs: conda-matrix
     strategy:
       matrix:
-        python-version: ['3.10', 3.11]
-        numpy-version: [1.23, 1.24, 1.25, 1.26]
+        python-version: ${{ fromJson(needs.conda-matrix.outputs.python-version) }}
+        numpy-version: ${{ fromJson(needs.conda-matrix.outputs.numpy-version) }}
         include:
         - python-version: 3.12
           numpy-version: 1.26