diff --git a/env/merlin/spack.yaml b/env/merlin/spack.yaml
index 3a45d42..7ee628a 100644
--- a/env/merlin/spack.yaml
+++ b/env/merlin/spack.yaml
@@ -549,7 +549,7 @@ spack:
          python,root~tbb~x,slurm,gsl]
       - ['%gcc']
     - matrix:
-      - [boost, hdf5~mpi, openmpi]
+      - [boost]
       - ['%clang','%gcc','%nvhpc','%oneapi']
     - matrix:
       - [hdf5~mpi, openmpi]