diff --git a/.github/workflows/unit_tests.yml b/.github/workflows/unit_tests.yml
index 7c7bf2c36b..288acdbd4c 100644
--- a/.github/workflows/unit_tests.yml
+++ b/.github/workflows/unit_tests.yml
@@ -27,6 +27,7 @@ jobs:
           if [ "${{ matrix.os }}" == "ubuntu-latest" ]; then
             sudo add-apt-repository ppa:ubuntu-toolchain-r/test
             sudo apt-get update
+            sudo apt-get install libopenmpi-dev openmpi-bin
           fi;
       - name: Install dependencies
         shell: bash -el {0}
@@ -34,7 +35,11 @@ jobs:
           python -m pip install --upgrade pip
           pip install flake8 pytest pytest-cov
           pip install psutil joblib
-          conda install --yes -c conda-forge mpi4py openmpi
+          if [ "${{ matrix.os }}" == "ubuntu-latest" ]; then
+            pip install mpi4py
+          else
+            conda install --yes mpi4py openmpi
+          fi
       - name: Install HNN-core
         shell: bash -el {0}
         run: |