diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 0068af3331e56c718839c9605b77edc16af7e641..4e69beadbe991abec364378ee0df83be5e69da23 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -85,15 +85,17 @@ jobs:
                 cd "$DOWNSTREAM_PROJECT"
                 echo "*** $DOWNSTREAM_PROJECT version: $(git rev-parse --short HEAD)"
                 sed -i "/egg=grudge/ c git+file://$(readlink -f ..)#egg=grudge" requirements.txt
-                export CONDA_ENVIRONMENT=.test-conda-env-py3.yml
                 # Avoid slow or complicated tests in downstream projects
                 export PYTEST_ADDOPTS="-k 'not (slowtest or octave or mpi)'"
                 if test "$DOWNSTREAM_PROJECT" = "mirgecom"; then
                     # can't turn off MPI in mirgecom
                     sudo apt-get update
                     sudo apt-get install openmpi-bin libopenmpi-dev
+                    export CONDA_ENVIRONMENT=conda-env.yml
                 else
                     sed -i "/mpi4py/ d" requirements.txt
+                    export CONDA_ENVIRONMENT=.test-conda-env-py3.yml
+
                 fi
                 curl -L -O -k https://gitlab.tiker.net/inducer/ci-support/raw/master/ci-support.sh
                 . ./ci-support.sh