diff --git a/env/merlin/spack.yaml b/env/merlin/spack.yaml
index 939c7ad..3a45d42 100644
--- a/env/merlin/spack.yaml
+++ b/env/merlin/spack.yaml
@@ -545,15 +545,15 @@ spack:
 #<<<
   specs:
     - matrix: 
-      - [cmake,cuda,fftw,gromacs,kokkos,mpich netmod=ucx,nvhpc,openblas threads=none,openblas threads=openmp,
+      - [cmake,cuda,fftw,gromacs,kokkos,mpich netmod=ucx,nvhpc+mpi,openblas threads=none,openblas threads=openmp,
          python,root~tbb~x,slurm,gsl]
       - ['%gcc']
     - matrix:
       - [boost, hdf5~mpi, openmpi]
       - ['%clang','%gcc','%nvhpc','%oneapi']
-      exclude:
-      - hdf5~mpi%clang
-      - openmpi%clang
+    - matrix:
+      - [hdf5~mpi, openmpi]
+      - ['%gcc','%oneapi']
     - matrix:
       - [hdf5+mpi +fortran +hl +shared, netcdf-fortran, netcdf-c +parallel-netcdf]
       - ['%gcc','%nvhpc','%oneapi']