diff --git a/spack.yaml b/spack.yaml
index 95ed9cc..b02c85b 100644
--- a/spack.yaml
+++ b/spack.yaml
@@ -4,33 +4,69 @@
 # configuration settings.
 spack:
   definitions:
-  - compilers:
-    - intel@2021.10.0
+  # - compilers:
+  #   - intel@2021.10.0
+  # FIXME: What is to be done with the definitions for 'mpis' and 'serial_packages'
   - mpis:
     - openmpi@4.1.5
   - serial_packages:
     - fortranxml@4.1.2
-  - packages:
-    - esmf@8.5.0+debug
-    - parallelio@2.6.2 build_type=RelWithDebInfo fflags='-qno-opt-dynamic-align -convert
-      big_endian -assume byterecl -ftz -traceback -assume realloc_lhs -fp-model source'
-      cflags='-qno-opt-dynamic-align -fp-model precise -std=gnu99'
-    - netcdf-c@4.9.2 build_system=cmake build_type=RelWithDebInfo
-    - netcdf-fortran@4.6.1
-    - fms@2023.02 precision=64 +large_file +deprecated_io ~gfs_phys ~openmp ~quad_precision
-      build_type=RelWithDebInfo
-    - access-om3 +install_libraries
+  # - packages:
+  #   - esmf@8.5.0+debug
+  #   - parallelio@2.6.2 build_type=RelWithDebInfo fflags='-qno-opt-dynamic-align -convert
+  #     big_endian -assume byterecl -ftz -traceback -assume realloc_lhs -fp-model source'
+  #     cflags='-qno-opt-dynamic-align -fp-model precise -std=gnu99'
+  #   - netcdf-c@4.9.2 build_system=cmake build_type=RelWithDebInfo
+  #   - netcdf-fortran@4.6.1
+  #   - fms@2023.02 precision=64 +large_file +deprecated_io ~gfs_phys ~openmp ~quad_precision
+  #     build_type=RelWithDebInfo
+  #   - access-om3 +install_libraries
   specs:
-  - matrix:
-    - [$mpis]
-    - [$%compilers]
-  - matrix:
-    - [$packages]
-    - [$^mpis]
-    - [$%compilers]
-  - matrix:
-    - [$serial_packages]
-    - [$%compilers]
+  - access-om3-virtual@git.2024.04.0  # FIXME: Add appropriate first version
+  packages:
+    access-om3:
+      require:
+        - '@git.v0.2.0'
+        - '+install_libraries'
+    esmf:
+      require:
+        - '@8.5.0'
+        - '+debug'
+    parallelio:
+      require:
+        - '@2.6.2'
+        - 'build_type=RelWithDebInfo fflags='-qno-opt-dynamic-align -convert'
+        - 'big_endian -assume byterecl -ftz -traceback -assume realloc_lhs -fp-model source'
+        - 'cflags='-qno-opt-dynamic-align -fp-model precise -std=gnu99'
+    netcdf-c:
+      require:
+        - '@4.9.2'
+        - 'build_system=cmake build_type=RelWithDebInfo'
+    netcdf-fortran:
+      require:
+        - '@4.6.1'
+    fms:
+      require:
+        - '@2023.02'
+        - 'precision=64 +large_file +deprecated_io ~gfs_phys ~openmp ~quad_precision'
+        - 'build_type=RelWithDebInfo'
+    openmpi:
+      require:
+        - '@4.1.5'
+
+    all:
+      compiler: [intel@19.0.5.281]
+
+  # - matrix:
+  #   - [$mpis]
+  #   - [$%compilers]
+  # - matrix:
+  #   - [$packages]
+  #   - [$^mpis]
+  #   - [$%compilers]
+  # - matrix:
+  #   - [$serial_packages]
+  #   - [$%compilers]
   view: true
   concretizer:
     unify: true