diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index e76d508effee9ce57f18dbf4c46683879f110f06..f82e332a6853b8438cb14b9189cea55f32ef86f2 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -71,6 +71,7 @@ jobs:
         -   uses: actions/checkout@v2
         -   name: "Main Script"
             run: |
+                echo "- matplotlib" >> .test-conda-env-py3.yml
                 curl -L -O https://gitlab.tiker.net/inducer/ci-support/raw/main/ci-support.sh
                 . ci-support.sh
                 build_py_project_in_conda_env