diff --git a/.github/workflows/mopper-conda.yaml b/.github/workflows/mopper-conda.yaml
index f32f3a4..5ff395e 100644
--- a/.github/workflows/mopper-conda.yaml
+++ b/.github/workflows/mopper-conda.yaml
@@ -40,7 +40,7 @@ jobs:
         flake8 . --count --exit-zero --max-complexity=10 --max-line-length=127 --statistics
     - name: Test with pytest
       run: |
-        conda install pytest coverage codecov
+        conda install pytest coverage codecov --solver classic
         conda run python -m pytest
         conda run coverage run --source src -m py.test
     - name: Upload to codecov