diff --git a/.github/workflows/pyop2.yml b/.github/workflows/pyop2.yml
index e6bafb8dd6..0eb2ef2813 100644
--- a/.github/workflows/pyop2.yml
+++ b/.github/workflows/pyop2.yml
@@ -106,9 +106,10 @@ jobs:
         working-directory: PyOP2
         run: |
           source ../venv/bin/activate
+          export CC=mpicc
           export HDF5_DIR="$PETSC_DIR/$PETSC_ARCH"
           export HDF5_MPI=ON
-          python -m pip install -v ".[test]"
+          python -m pip install --no-binary h5py -v ".[test]"
 
       - name: Run tests
         shell: bash