diff --git a/.github/workflows/basic.yml b/.github/workflows/basic.yml
index cb9e80e7492517b71a8a30dc3ff805d599ae67d6..ecabaf8e857a223a4e645da3a2ecda38d99fccca 100644
--- a/.github/workflows/basic.yml
+++ b/.github/workflows/basic.yml
@@ -88,6 +88,9 @@ jobs:
         CXX:        ${{ matrix.config.cxx }}
         # We set PYTHONPATH instead of installing arbor to avoid distribution/OS specific behaviour.
         PYTHONPATH: ${{ github.workspace }}/build/python
+        # This is a workaround for the unfortunate interaction of MacOS and OpenMPI 4
+        # See https://github.com/open-mpi/ompi/issues/6518
+        OMPI_MCA_btl: "self,tcp"
     steps:
       - name: Set up cmake
         uses: jwlawson/actions-setup-cmake@v1.7