diff --git a/src/io4dolfinx/backends/__init__.py b/src/io4dolfinx/backends/__init__.py
index d9702f4..8f2726d 100644
--- a/src/io4dolfinx/backends/__init__.py
+++ b/src/io4dolfinx/backends/__init__.py
@@ -75,7 +75,7 @@ def get_default_backend_args(self, arguments: dict[str, Any] | None) -> dict[str
     def write_attributes(
         self,
         filename: Path | str,
-        comm: MPI.Intracomm,
+        comm: MPI.Comm,
         name: str,
         attributes: dict[str, np.ndarray],
         backend_args: dict[str, Any] | None,
@@ -93,7 +93,7 @@ def write_attributes(
     def read_attributes(
         self,
         filename: Path | str,
-        comm: MPI.Intracomm,
+        comm: MPI.Comm,
         name: str,
         backend_args: dict[str, Any] | None,
     ) -> dict[str, Any]:
@@ -112,7 +112,7 @@ def read_attributes(
     def read_timestamps(
         self,
         filename: Path | str,
-        comm: MPI.Intracomm,
+        comm: MPI.Comm,
         function_name: str,
         backend_args: dict[str, Any] | None,
     ) -> npt.NDArray[np.float64 | str]:  # type: ignore[type-var]
@@ -131,7 +131,7 @@ def read_timestamps(
     def write_mesh(
         self,
         filename: Path | str,
-        comm: MPI.Intracomm,
+        comm: MPI.Comm,
         mesh: MeshData,
         backend_args: dict[str, Any] | None,
         mode: FileMode,
@@ -152,7 +152,7 @@ def write_mesh(
     def write_meshtags(
         self,
         filename: str | Path,
-        comm: MPI.Intracomm,
+        comm: MPI.Comm,
         data: MeshTagsData,
         backend_args: dict[str, Any] | None,
     ):
@@ -168,7 +168,7 @@ def write_meshtags(
     def read_mesh_data(
         self,
         filename: Path | str,
-        comm: MPI.Intracomm,
+        comm: MPI.Comm,
         time: str | float | None,
         read_from_partition: bool,
         backend_args: dict[str, Any] | None,
@@ -189,7 +189,7 @@ def read_mesh_data(
     def read_meshtags_data(
         self,
         filename: str | Path,
-        comm: MPI.Intracomm,
+        comm: MPI.Comm,
         name: str,
         backend_args: dict[str, Any] | None,
     ) -> MeshTagsData:
@@ -208,7 +208,7 @@ def read_meshtags_data(
     def read_dofmap(
         self,
         filename: str | Path,
-        comm: MPI.Intracomm,
+        comm: MPI.Comm,
         name: str,
         backend_args: dict[str, Any] | None,
     ) -> dolfinx.graph.AdjacencyList:
@@ -227,7 +227,7 @@ def read_dofmap(
     def read_dofs(
         self,
         filename: str | Path,
-        comm: MPI.Intracomm,
+        comm: MPI.Comm,
         name: str,
         time: float,
         backend_args: dict[str, Any] | None,
@@ -248,7 +248,7 @@ def read_dofs(
         """
 
     def read_cell_perms(
-        self, comm: MPI.Intracomm, filename: Path | str, backend_args: dict[str, Any] | None
+        self, comm: MPI.Comm, filename: Path | str, backend_args: dict[str, Any] | None
     ) -> npt.NDArray[np.uint32]:
         """
         Read cell permutation from file with given communicator,
@@ -267,7 +267,7 @@ def read_cell_perms(
     def write_function(
         self,
         filename: Path,
-        comm: MPI.Intracomm,
+        comm: MPI.Comm,
         u: FunctionData,
         time: float,
         mode: FileMode,
@@ -285,7 +285,7 @@ def write_function(
         """
 
     def read_legacy_mesh(
-        self, filename: Path | str, comm: MPI.Intracomm, group: str
+        self, filename: Path | str, comm: MPI.Comm, group: str
     ) -> tuple[npt.NDArray[np.int64], npt.NDArray[np.floating], str | None]:
         """Read in the mesh topology, geometry and (optionally) cell type from a
         legacy DOLFIN HDF5-file.
@@ -320,7 +320,7 @@ def snapshot_checkpoint(
 
     def read_hdf5_array(
         self,
-        comm: MPI.Intracomm,
+        comm: MPI.Comm,
         filename: Path | str,
         group: str,
         backend_args: dict[str, Any] | None,
@@ -344,7 +344,7 @@ def read_point_data(
         self,
         filename: Path | str,
         name: str,
-        comm: MPI.Intracomm,
+        comm: MPI.Comm,
         time: str | float | None,
         backend_args: dict[str, Any] | None,
     ) -> tuple[np.ndarray, int]:
@@ -362,7 +362,7 @@ def read_point_data(
         ...
 
     def read_function_names(
-        self, filename: Path | str, comm: MPI.Intracomm, backend_args: dict[str, Any] | None
+        self, filename: Path | str, comm: MPI.Comm, backend_args: dict[str, Any] | None
     ) -> list[str]:
         """Read all function names from a file.
 
@@ -380,7 +380,7 @@ def read_cell_data(
         self,
         filename: Path | str,
         name: str,
-        comm: MPI.Intracomm,
+        comm: MPI.Comm,
         time: str | float | None,
         backend_args: dict[str, Any] | None,
     ) -> tuple[npt.NDArray[np.int64], np.ndarray]:
@@ -403,7 +403,7 @@ def write_data(
         self,
         filename: Path | str,
         array_data: ArrayData,
-        comm: MPI.Intracomm,
+        comm: MPI.Comm,
         time: str | float | None,
         mode: FileMode,
         backend_args: dict[str, Any] | None,
diff --git a/src/io4dolfinx/backends/adios2/backend.py b/src/io4dolfinx/backends/adios2/backend.py
index 0f547bd..a4024cd 100644
--- a/src/io4dolfinx/backends/adios2/backend.py
+++ b/src/io4dolfinx/backends/adios2/backend.py
@@ -50,7 +50,7 @@ def convert_file_mode(mode: FileMode) -> adios2.Mode:  # type: ignore[override]
 
 def write_attributes(
     filename: Path | str,
-    comm: MPI.Intracomm,
+    comm: MPI.Comm,
     name: str,
     attributes: dict[str, np.ndarray],
     backend_args: dict[str, Any] | None = None,
@@ -86,7 +86,7 @@ def write_attributes(
 
 def read_attributes(
     filename: Path | str,
-    comm: MPI.Intracomm,
+    comm: MPI.Comm,
     name: str,
     backend_args: dict[str, Any] | None = None,
 ) -> dict[str, np.ndarray]:
@@ -122,7 +122,7 @@ def read_attributes(
 
 def read_timestamps(
     filename: Path | str,
-    comm: MPI.Intracomm,
+    comm: MPI.Comm,
     function_name: str,
     backend_args: dict[str, Any] | None = None,
 ) -> npt.NDArray[np.float64 | str]:  # type: ignore[type-var]
@@ -169,7 +169,7 @@ def read_timestamps(
 
 def write_mesh(
     filename: Path | str,
-    comm: MPI.Intracomm,
+    comm: MPI.Comm,
     mesh: MeshData,
     backend_args: dict[str, Any] | None = None,
     mode: FileMode = FileMode.write,
@@ -277,7 +277,7 @@ def write_mesh(
 
 def read_mesh_data(
     filename: Path | str,
-    comm: MPI.Intracomm,
+    comm: MPI.Comm,
     time: str | float | None = 0.0,
     read_from_partition: bool = False,
     backend_args: dict[str, Any] | None = None,
@@ -409,7 +409,7 @@ def read_mesh_data(
 
 def write_meshtags(
     filename: str | Path,
-    comm: MPI.Intracomm,
+    comm: MPI.Comm,
     data: MeshTagsData,
     backend_args: dict[str, Any] | None = None,
 ):
@@ -462,7 +462,7 @@ def write_meshtags(
 
 
 def read_meshtags_data(
-    filename: str | Path, comm: MPI.Intracomm, name: str, backend_args: dict[str, Any] | None = None
+    filename: str | Path, comm: MPI.Comm, name: str, backend_args: dict[str, Any] | None = None
 ) -> MeshTagsData:
     """Read mesh tags from file.
 
@@ -600,7 +600,7 @@ def read_meshtags_data(
 
 
 def read_dofmap(
-    filename: str | Path, comm: MPI.Intracomm, name: str, backend_args: dict[str, Any] | None = None
+    filename: str | Path, comm: MPI.Comm, name: str, backend_args: dict[str, Any] | None = None
 ) -> dolfinx.graph.AdjacencyList:
     """Read the dofmap of a function with a given name.
 
@@ -641,7 +641,7 @@ def read_dofmap(
 
 def read_dofs(
     filename: str | Path,
-    comm: MPI.Intracomm,
+    comm: MPI.Comm,
     name: str,
     time: float,
     backend_args: dict[str, Any] | None = None,
@@ -698,7 +698,7 @@ def read_dofs(
 
 
 def read_cell_perms(
-    comm: MPI.Intracomm, filename: Path | str, backend_args: dict[str, Any] | None = None
+    comm: MPI.Comm, filename: Path | str, backend_args: dict[str, Any] | None = None
 ) -> npt.NDArray[np.uint32]:
     """
     Read cell permutation from file with given communicator,
@@ -733,7 +733,7 @@ def read_cell_perms(
 
 
 def read_hdf5_array(
-    comm: MPI.Intracomm,
+    comm: MPI.Comm,
     filename: Path | str,
     group: str,
     backend_args: dict[str, Any] | None = None,
@@ -758,7 +758,7 @@ def read_hdf5_array(
 
 def write_function(
     filename: Path,
-    comm: MPI.Intracomm,
+    comm: MPI.Comm,
     u: FunctionData,
     time: float = 0.0,
     mode: FileMode = FileMode.append,
@@ -854,7 +854,7 @@ def write_function(
 
 
 def read_legacy_mesh(
-    filename: Path | str, comm: MPI.Intracomm, group: str
+    filename: Path | str, comm: MPI.Comm, group: str
 ) -> tuple[npt.NDArray[np.int64], npt.NDArray[np.floating], str | None]:
     """Read in the mesh topology, geometry and (optionally) cell type from a
     legacy DOLFIN HDF5-file.
@@ -970,7 +970,7 @@ def snapshot_checkpoint(
 
 
 def read_function_names(
-    filename: Path | str, comm: MPI.Intracomm, backend_args: dict[str, Any] | None
+    filename: Path | str, comm: MPI.Comm, backend_args: dict[str, Any] | None
 ) -> list[str]:
     """Read all function names from a file.
 
@@ -988,7 +988,7 @@ def read_function_names(
 def read_point_data(
     filename: Path | str,
     name: str,
-    comm: MPI.Intracomm,
+    comm: MPI.Comm,
     time: float | str | None,
     backend_args: dict[str, Any] | None,
 ) -> tuple[np.ndarray, int]:
@@ -1010,7 +1010,7 @@ def read_point_data(
 def read_cell_data(
     filename: Path | str,
     name: str,
-    comm: MPI.Intracomm,
+    comm: MPI.Comm,
     time: str | float | None,
     backend_args: dict[str, Any] | None,
 ) -> tuple[npt.NDArray[np.int64], np.ndarray]:
@@ -1033,7 +1033,7 @@ def read_cell_data(
 def write_data(
     filename: Path | str,
     array_data: ArrayData,
-    comm: MPI.Intracomm,
+    comm: MPI.Comm,
     time: str | float | None,
     mode: FileMode,
     backend_args: dict[str, Any] | None,
diff --git a/src/io4dolfinx/backends/adios2/helpers.py b/src/io4dolfinx/backends/adios2/helpers.py
index 9f7909f..be2b912 100644
--- a/src/io4dolfinx/backends/adios2/helpers.py
+++ b/src/io4dolfinx/backends/adios2/helpers.py
@@ -12,12 +12,11 @@
 from mpi4py import MPI
 
 import adios2
-import dolfinx.cpp.graph
 import dolfinx.graph
 import numpy as np
 import numpy.typing as npt
 
-from io4dolfinx.utils import compute_local_range, valid_function_types
+from ...utils import compute_local_range, valid_function_types
 
 
 def resolve_adios_scope(adios2):
@@ -60,7 +59,7 @@ def ADIOSFile(
     engine: str,
     mode: adios2.Mode,
     io_name: str,
-    comm: MPI.Intracomm | None = None,
+    comm: MPI.Comm | None = None,
 ):
     io = adios.DeclareIO(io_name)
     io.SetEngine(engine)
@@ -118,7 +117,7 @@ def check_variable_exists(
 
 def read_adjacency_list(
     adios: adios2.ADIOS,
-    comm: MPI.Intracomm,
+    comm: MPI.Comm,
     filename: Path | str,
     data_name: str,
     offsets_name: str,
@@ -221,7 +220,7 @@ def read_array(
     filename: Path | str,
     array_name: str,
     engine: str,
-    comm: MPI.Intracomm,
+    comm: MPI.Comm,
     time: float = 0.0,
     time_name: str = "",
     legacy: bool = False,
diff --git a/src/io4dolfinx/backends/exodus/backend.py b/src/io4dolfinx/backends/exodus/backend.py
index ab2e4df..06a7e5e 100644
--- a/src/io4dolfinx/backends/exodus/backend.py
+++ b/src/io4dolfinx/backends/exodus/backend.py
@@ -95,7 +95,7 @@ def convert_file_mode(mode: FileMode) -> str:
 
 def write_attributes(
     filename: Path | str,
-    comm: MPI.Intracomm,
+    comm: MPI.Comm,
     name: str,
     attributes: dict[str, np.ndarray],
     backend_args: dict[str, Any] | None = None,
@@ -114,7 +114,7 @@ def write_attributes(
 
 def read_attributes(
     filename: Path | str,
-    comm: MPI.Intracomm,
+    comm: MPI.Comm,
     name: str,
     backend_args: dict[str, Any] | None = None,
 ) -> dict[str, Any]:
@@ -149,7 +149,7 @@ def snapshot_checkpoint(
 
 
 def read_hdf5_array(
-    comm: MPI.Intracomm,
+    comm: MPI.Comm,
     filename: Path | str,
     group: str,
     backend_args: dict[str, Any] | None,
@@ -173,7 +173,7 @@ def read_hdf5_array(
 
 def read_timestamps(
     filename: Path | str,
-    comm: MPI.Intracomm,
+    comm: MPI.Comm,
     function_name: str,
     backend_args: dict[str, Any] | None = None,
 ) -> npt.NDArray[np.float64 | str]:  # type: ignore[type-var]
@@ -194,7 +194,7 @@ def read_timestamps(
 
 def write_mesh(
     filename: Path | str,
-    comm: MPI.Intracomm,
+    comm: MPI.Comm,
     mesh: MeshData,
     backend_args: dict[str, Any] | None = None,
     mode: FileMode = FileMode.write,
@@ -273,7 +273,7 @@ def _extract_connectivity_data(
 
 def read_mesh_data(
     filename: Path | str,
-    comm: MPI.Intracomm,
+    comm: MPI.Comm,
     time: str | float | None = 0.0,
     read_from_partition: bool = False,
     backend_args: dict[str, Any] | None = None,
@@ -371,7 +371,7 @@ def read_mesh_data(
 
 def write_meshtags(
     filename: str | Path,
-    comm: MPI.Intracomm,
+    comm: MPI.Comm,
     data: MeshTagsData,
     backend_args: dict[str, Any] | None = None,
 ):
@@ -388,7 +388,7 @@ def write_meshtags(
 
 def read_meshtags_data(
     filename: str | Path,
-    comm: MPI.Intracomm,
+    comm: MPI.Comm,
     name: str,
     backend_args: dict[str, Any] | None = None,
 ) -> MeshTagsData:
@@ -506,7 +506,7 @@ def read_meshtags_data(
 
 def read_dofmap(
     filename: str | Path,
-    comm: MPI.Intracomm,
+    comm: MPI.Comm,
     name: str,
     backend_args: dict[str, Any] | None,
 ) -> dolfinx.graph.AdjacencyList:
@@ -526,7 +526,7 @@ def read_dofmap(
 
 def read_dofs(
     filename: str | Path,
-    comm: MPI.Intracomm,
+    comm: MPI.Comm,
     name: str,
     time: float,
     backend_args: dict[str, Any] | None,
@@ -549,7 +549,7 @@ def read_dofs(
 
 
 def read_cell_perms(
-    comm: MPI.Intracomm, filename: Path | str, backend_args: dict[str, Any] | None
+    comm: MPI.Comm, filename: Path | str, backend_args: dict[str, Any] | None
 ) -> npt.NDArray[np.uint32]:
     """
     Read cell permutation from file with given communicator,
@@ -570,7 +570,7 @@ def read_cell_perms(
 
 def write_function(
     filename: str | Path,
-    comm: MPI.Intracomm,
+    comm: MPI.Comm,
     u: FunctionData,
     time: float,
     mode: FileMode,
@@ -591,7 +591,7 @@ def write_function(
 
 
 def read_legacy_mesh(
-    filename: Path | str, comm: MPI.Intracomm, group: str
+    filename: Path | str, comm: MPI.Comm, group: str
 ) -> tuple[npt.NDArray[np.int64], npt.NDArray[np.floating], str | None]:
     """Read in the mesh topology, geometry and (optionally) cell type from a
     legacy DOLFIN HDF5-file.
@@ -613,7 +613,7 @@ def read_legacy_mesh(
 def read_point_data(
     filename: Path | str,
     name: str,
-    comm: MPI.Intracomm,
+    comm: MPI.Comm,
     time: float | str | None,
     backend_args: dict[str, Any] | None,
 ) -> tuple[np.ndarray, int]:
@@ -669,7 +669,7 @@ def read_point_data(
 def read_cell_data(
     filename: Path | str,
     name: str,
-    comm: MPI.Intracomm,
+    comm: MPI.Comm,
     time: str | float | None,
     backend_args: dict[str, Any] | None,
 ) -> tuple[npt.NDArray[np.int64], np.ndarray]:
@@ -738,7 +738,7 @@ def read_cell_data(
 
 
 def read_function_names(
-    filename: Path | str, comm: MPI.Intracomm, backend_args: dict[str, Any] | None
+    filename: Path | str, comm: MPI.Comm, backend_args: dict[str, Any] | None
 ) -> list[str]:
     """Read all function names from a file.
 
@@ -762,7 +762,7 @@ def read_function_names(
 def write_data(
     filename: Path | str,
     array_data: ArrayData,
-    comm: MPI.Intracomm,
+    comm: MPI.Comm,
     time: str | float | None,
     mode: FileMode,
     backend_args: dict[str, Any] | None,
diff --git a/src/io4dolfinx/backends/h5py/backend.py b/src/io4dolfinx/backends/h5py/backend.py
index 31c56c7..aa8e4bc 100644
--- a/src/io4dolfinx/backends/h5py/backend.py
+++ b/src/io4dolfinx/backends/h5py/backend.py
@@ -79,7 +79,7 @@ def convert_file_mode(mode: FileMode) -> str:
 
 def write_attributes(
     filename: Path | str,
-    comm: MPI.Intracomm,
+    comm: MPI.Comm,
     name: str,
     attributes: dict[str, np.ndarray],
     backend_args: dict[str, Any] | None = None,
@@ -105,7 +105,7 @@ def write_attributes(
 
 def read_attributes(
     filename: Path | str,
-    comm: MPI.Intracomm,
+    comm: MPI.Comm,
     name: str,
     backend_args: dict[str, Any] | None = None,
 ) -> dict[str, Any]:
@@ -128,7 +128,7 @@ def read_attributes(
 
 def read_timestamps(
     filename: Path | str,
-    comm: MPI.Intracomm,
+    comm: MPI.Comm,
     function_name: str,
     backend_args: dict[str, Any] | None = None,
 ) -> npt.NDArray[np.float64 | str]:  # type: ignore[type-var]
@@ -155,7 +155,7 @@ def read_timestamps(
 
 def write_mesh(
     filename: Path | str,
-    comm: MPI.Intracomm,
+    comm: MPI.Comm,
     mesh: MeshData,
     backend_args: dict[str, Any] | None = None,
     mode: FileMode = FileMode.write,
@@ -237,7 +237,7 @@ def write_mesh(
 
 def read_mesh_data(
     filename: Path | str,
-    comm: MPI.Intracomm,
+    comm: MPI.Comm,
     time: str | float | None = 0.0,
     read_from_partition: bool = False,
     backend_args: dict[str, Any] | None = None,
@@ -319,7 +319,7 @@ def read_mesh_data(
 
 def write_meshtags(
     filename: str | Path,
-    comm: MPI.Intracomm,
+    comm: MPI.Comm,
     data: MeshTagsData,
     backend_args: dict[str, Any] | None = None,
 ):
@@ -366,7 +366,7 @@ def write_meshtags(
 
 
 def read_meshtags_data(
-    filename: str | Path, comm: MPI.Intracomm, name: str, backend_args: dict[str, Any] | None = None
+    filename: str | Path, comm: MPI.Comm, name: str, backend_args: dict[str, Any] | None = None
 ) -> MeshTagsData:
     """Read mesh tags from file.
 
@@ -415,7 +415,7 @@ def read_meshtags_data(
 
 
 def read_dofmap(
-    filename: str | Path, comm: MPI.Intracomm, name: str, backend_args: dict[str, Any] | None
+    filename: str | Path, comm: MPI.Comm, name: str, backend_args: dict[str, Any] | None
 ) -> dolfinx.graph.AdjacencyList:
     """Read the dofmap of a function with a given name.
 
@@ -470,7 +470,7 @@ def read_dofmap(
 
 def read_dofs(
     filename: str | Path,
-    comm: MPI.Intracomm,
+    comm: MPI.Comm,
     name: str,
     time: float,
     backend_args: dict[str, Any] | None,
@@ -515,7 +515,7 @@ def read_dofs(
 
 
 def read_cell_perms(
-    comm: MPI.Intracomm, filename: Path | str, backend_args: dict[str, Any] | None
+    comm: MPI.Comm, filename: Path | str, backend_args: dict[str, Any] | None
 ) -> npt.NDArray[np.uint32]:
     """
     Read cell permutation from file with given communicator,
@@ -545,7 +545,7 @@ def read_cell_perms(
 
 def write_function(
     filename: str | Path,
-    comm: MPI.Intracomm,
+    comm: MPI.Comm,
     u: FunctionData,
     time: float,
     mode: FileMode,
@@ -625,7 +625,7 @@ def write_function(
 
 
 def read_legacy_mesh(
-    filename: Path | str, comm: MPI.Intracomm, group: str
+    filename: Path | str, comm: MPI.Comm, group: str
 ) -> tuple[npt.NDArray[np.int64], npt.NDArray[np.floating], str | None]:
     """Read in the mesh topology, geometry and (optionally) cell type from a
     legacy DOLFIN HDF5-file.
@@ -677,7 +677,7 @@ def read_legacy_mesh(
 
 
 def read_hdf5_array(
-    comm: MPI.Intracomm,
+    comm: MPI.Comm,
     filename: Path | str,
     group: str,
     backend_args: dict[str, Any] | None = None,
@@ -739,7 +739,7 @@ def snapshot_checkpoint(
 
 
 def read_function_names(
-    filename: Path | str, comm: MPI.Intracomm, backend_args: dict[str, Any] | None
+    filename: Path | str, comm: MPI.Comm, backend_args: dict[str, Any] | None
 ) -> list[str]:
     """Read all function names from a file.
 
@@ -767,7 +767,7 @@ def read_function_names(
 def read_point_data(
     filename: Path | str,
     name: str,
-    comm: MPI.Intracomm,
+    comm: MPI.Comm,
     time: float | str | None,
     backend_args: dict[str, Any] | None,
 ) -> tuple[np.ndarray, int]:
@@ -789,7 +789,7 @@ def read_point_data(
 def read_cell_data(
     filename: Path | str,
     name: str,
-    comm: MPI.Intracomm,
+    comm: MPI.Comm,
     time: str | float | None,
     backend_args: dict[str, Any] | None,
 ) -> tuple[npt.NDArray[np.int64], np.ndarray]:
@@ -812,7 +812,7 @@ def read_cell_data(
 def write_data(
     filename: Path | str,
     array_data: ArrayData,
-    comm: MPI.Intracomm,
+    comm: MPI.Comm,
     time: str | float | None,
     mode: FileMode,
     backend_args: dict[str, Any] | None,
diff --git a/src/io4dolfinx/backends/pyvista/backend.py b/src/io4dolfinx/backends/pyvista/backend.py
index 0dcf0b7..261c47a 100644
--- a/src/io4dolfinx/backends/pyvista/backend.py
+++ b/src/io4dolfinx/backends/pyvista/backend.py
@@ -117,7 +117,7 @@ def get_default_backend_args(arguments: dict[str, Any] | None) -> dict[str, Any]
 
 def read_mesh_data(
     filename: Path | str,
-    comm: MPI.Intracomm,
+    comm: MPI.Comm,
     time: str | float | None = None,
     read_from_partition: bool = False,
     backend_args: dict[str, Any] | None = None,
@@ -197,7 +197,7 @@ def read_mesh_data(
 def read_point_data(
     filename: Path | str,
     name: str,
-    comm: MPI.Intracomm,
+    comm: MPI.Comm,
     time: float | str | None,
     backend_args: dict[str, Any] | None,
 ) -> tuple[np.ndarray, int]:
@@ -255,7 +255,7 @@ def read_point_data(
 def read_cell_data(
     filename: Path | str,
     name: str,
-    comm: MPI.Intracomm,
+    comm: MPI.Comm,
     time: str | float | None,
     backend_args: dict[str, Any] | None,
 ) -> tuple[npt.NDArray[np.int64], np.ndarray]:
@@ -301,7 +301,7 @@ def read_cell_data(
 
 def write_attributes(
     filename: Path | str,
-    comm: MPI.Intracomm,
+    comm: MPI.Comm,
     name: str,
     attributes: dict[str, np.ndarray],
     backend_args: dict[str, Any] | None,
@@ -320,7 +320,7 @@ def write_attributes(
 
 def read_attributes(
     filename: Path | str,
-    comm: MPI.Intracomm,
+    comm: MPI.Comm,
     name: str,
     backend_args: dict[str, Any] | None,
 ) -> dict[str, Any]:
@@ -340,7 +340,7 @@ def read_attributes(
 
 def read_timestamps(
     filename: Path | str,
-    comm: MPI.Intracomm,
+    comm: MPI.Comm,
     function_name: str,
     backend_args: dict[str, Any] | None,
 ) -> npt.NDArray[np.float64 | str]:  # type: ignore[type-var]
@@ -359,7 +359,7 @@ def read_timestamps(
 
 
 def read_function_names(
-    filename: Path | str, comm: MPI.Intracomm, backend_args: dict[str, Any] | None
+    filename: Path | str, comm: MPI.Comm, backend_args: dict[str, Any] | None
 ) -> list[str]:
     """Read all function names from a file.
 
@@ -394,7 +394,7 @@ def read_function_names(
 
 def write_mesh(
     filename: Path | str,
-    comm: MPI.Intracomm,
+    comm: MPI.Comm,
     mesh: MeshData,
     backend_args: dict[str, Any] | None,
     mode: FileMode,
@@ -416,7 +416,7 @@ def write_mesh(
 
 def write_meshtags(
     filename: str | Path,
-    comm: MPI.Intracomm,
+    comm: MPI.Comm,
     data: MeshTagsData,
     backend_args: dict[str, Any] | None,
 ):
@@ -433,7 +433,7 @@ def write_meshtags(
 
 def read_meshtags_data(
     filename: str | Path,
-    comm: MPI.Intracomm,
+    comm: MPI.Comm,
     name: str,
     backend_args: dict[str, Any] | None,
 ) -> MeshTagsData:
@@ -453,7 +453,7 @@ def read_meshtags_data(
 
 def read_dofmap(
     filename: str | Path,
-    comm: MPI.Intracomm,
+    comm: MPI.Comm,
     name: str,
     backend_args: dict[str, Any] | None,
 ) -> dolfinx.graph.AdjacencyList:
@@ -473,7 +473,7 @@ def read_dofmap(
 
 def read_dofs(
     filename: str | Path,
-    comm: MPI.Intracomm,
+    comm: MPI.Comm,
     name: str,
     time: float,
     backend_args: dict[str, Any] | None,
@@ -496,7 +496,7 @@ def read_dofs(
 
 
 def read_cell_perms(
-    comm: MPI.Intracomm, filename: Path | str, backend_args: dict[str, Any] | None
+    comm: MPI.Comm, filename: Path | str, backend_args: dict[str, Any] | None
 ) -> npt.NDArray[np.uint32]:
     """
     Read cell permutation from file with given communicator,
@@ -516,7 +516,7 @@ def read_cell_perms(
 
 def write_function(
     filename: Path,
-    comm: MPI.Intracomm,
+    comm: MPI.Comm,
     u: FunctionData,
     time: float,
     mode: FileMode,
@@ -537,7 +537,7 @@ def write_function(
 
 
 def read_legacy_mesh(
-    filename: Path | str, comm: MPI.Intracomm, group: str
+    filename: Path | str, comm: MPI.Comm, group: str
 ) -> tuple[npt.NDArray[np.int64], npt.NDArray[np.floating], str | None]:
     """Read in the mesh topology, geometry and (optionally) cell type from a
     legacy DOLFIN HDF5-file.
@@ -574,7 +574,7 @@ def snapshot_checkpoint(
 
 
 def read_hdf5_array(
-    comm: MPI.Intracomm,
+    comm: MPI.Comm,
     filename: Path | str,
     group: str,
     backend_args: dict[str, Any] | None,
@@ -599,7 +599,7 @@ def read_hdf5_array(
 def write_data(
     filename: Path | str,
     array_data: ArrayData,
-    comm: MPI.Intracomm,
+    comm: MPI.Comm,
     time: str | float | None,
     mode: FileMode,
     backend_args: dict[str, Any] | None,
diff --git a/src/io4dolfinx/backends/vtkhdf/backend.py b/src/io4dolfinx/backends/vtkhdf/backend.py
index e0c4b76..e4f1737 100644
--- a/src/io4dolfinx/backends/vtkhdf/backend.py
+++ b/src/io4dolfinx/backends/vtkhdf/backend.py
@@ -126,7 +126,7 @@ def _get_time_index(hdf: h5py.Group, time: float | str, filename: str | Path) ->
 
 def read_mesh_data(
     filename: Path | str,
-    comm: MPI.Intracomm,
+    comm: MPI.Comm,
     time: str | float | None,
     read_from_partition: bool,
     backend_args: dict[str, Any] | None,
@@ -236,7 +236,7 @@ def read_mesh_data(
 def read_point_data(
     filename: Path | str,
     name: str,
-    comm: MPI.Intracomm,
+    comm: MPI.Comm,
     time: float | str | None,
     backend_args: dict[str, Any] | None,
 ) -> tuple[np.ndarray, int]:
@@ -285,7 +285,7 @@ def read_point_data(
 def read_cell_data(
     filename: Path | str,
     name: str,
-    comm: MPI.Intracomm,
+    comm: MPI.Comm,
     time: str | float | None,
     backend_args: dict[str, Any] | None,
 ) -> tuple[npt.NDArray[np.int64], np.ndarray]:
@@ -335,7 +335,7 @@ def read_cell_data(
 
 def write_attributes(
     filename: Path | str,
-    comm: MPI.Intracomm,
+    comm: MPI.Comm,
     name: str,
     attributes: dict[str, np.ndarray],
     backend_args: dict[str, Any] | None,
@@ -354,7 +354,7 @@ def write_attributes(
 
 def read_attributes(
     filename: Path | str,
-    comm: MPI.Intracomm,
+    comm: MPI.Comm,
     name: str,
     backend_args: dict[str, Any] | None,
 ) -> dict[str, Any]:
@@ -374,7 +374,7 @@ def read_attributes(
 
 def read_timestamps(
     filename: Path | str,
-    comm: MPI.Intracomm,
+    comm: MPI.Comm,
     function_name: str,
     backend_args: dict[str, Any] | None,
 ) -> npt.NDArray[np.float64 | str]:  # type: ignore[type-var]
@@ -417,7 +417,7 @@ def read_timestamps(
 
 
 def read_function_names(
-    filename: Path | str, comm: MPI.Intracomm, backend_args: dict[str, Any] | None
+    filename: Path | str, comm: MPI.Comm, backend_args: dict[str, Any] | None
 ) -> list[str]:
     """Read all function names from a file.
 
@@ -497,7 +497,7 @@ def _compute_append_slice(
 
 def write_mesh(
     filename: Path | str,
-    comm: MPI.Intracomm,
+    comm: MPI.Comm,
     mesh: MeshData,
     backend_args: dict[str, Any] | None,
     mode: FileMode,
@@ -744,7 +744,7 @@ def write_mesh(
 
 def write_meshtags(
     filename: str | Path,
-    comm: MPI.Intracomm,
+    comm: MPI.Comm,
     data: MeshTagsData,
     backend_args: dict[str, Any] | None,
 ):
@@ -946,7 +946,7 @@ def write_meshtags(
 
 def read_meshtags_data(
     filename: str | Path,
-    comm: MPI.Intracomm,
+    comm: MPI.Comm,
     name: str,
     backend_args: dict[str, Any] | None,
 ) -> MeshTagsData:
@@ -985,7 +985,7 @@ def read_meshtags_data(
 
 def read_dofmap(
     filename: str | Path,
-    comm: MPI.Intracomm,
+    comm: MPI.Comm,
     name: str,
     backend_args: dict[str, Any] | None,
 ) -> dolfinx.graph.AdjacencyList:
@@ -1005,7 +1005,7 @@ def read_dofmap(
 
 def read_dofs(
     filename: str | Path,
-    comm: MPI.Intracomm,
+    comm: MPI.Comm,
     name: str,
     time: float,
     backend_args: dict[str, Any] | None,
@@ -1028,7 +1028,7 @@ def read_dofs(
 
 
 def read_cell_perms(
-    comm: MPI.Intracomm, filename: Path | str, backend_args: dict[str, Any] | None
+    comm: MPI.Comm, filename: Path | str, backend_args: dict[str, Any] | None
 ) -> npt.NDArray[np.uint32]:
     """
     Read cell permutation from file with given communicator,
@@ -1048,7 +1048,7 @@ def read_cell_perms(
 
 def write_function(
     filename: Path,
-    comm: MPI.Intracomm,
+    comm: MPI.Comm,
     u: FunctionData,
     time: float,
     mode: FileMode,
@@ -1069,7 +1069,7 @@ def write_function(
 
 
 def read_legacy_mesh(
-    filename: Path | str, comm: MPI.Intracomm, group: str
+    filename: Path | str, comm: MPI.Comm, group: str
 ) -> tuple[npt.NDArray[np.int64], npt.NDArray[np.floating], str | None]:
     """Read in the mesh topology, geometry and (optionally) cell type from a
     legacy DOLFIN HDF5-file.
@@ -1106,7 +1106,7 @@ def snapshot_checkpoint(
 
 
 def read_hdf5_array(
-    comm: MPI.Intracomm,
+    comm: MPI.Comm,
     filename: Path | str,
     group: str,
     backend_args: dict[str, Any] | None,
@@ -1131,7 +1131,7 @@ def read_hdf5_array(
 def write_data(
     filename: Path | str,
     array_data: ArrayData,
-    comm: MPI.Intracomm,
+    comm: MPI.Comm,
     time: str | float | None,
     mode: FileMode,
     backend_args: dict[str, Any] | None,
diff --git a/src/io4dolfinx/backends/xdmf/backend.py b/src/io4dolfinx/backends/xdmf/backend.py
index 8c4148e..1192240 100644
--- a/src/io4dolfinx/backends/xdmf/backend.py
+++ b/src/io4dolfinx/backends/xdmf/backend.py
@@ -59,7 +59,7 @@ def get_default_backend_args(arguments: dict[str, Any] | None) -> dict[str, Any]
 
 def read_mesh_data(
     filename: Path | str,
-    comm: MPI.Intracomm,
+    comm: MPI.Comm,
     time: str | float | None,
     read_from_partition: bool,
     backend_args: dict[str, Any] | None,
@@ -94,7 +94,7 @@ def read_mesh_data(
 def read_point_data(
     filename: Path | str,
     name: str,
-    comm: MPI.Intracomm,
+    comm: MPI.Comm,
     time: float | str | None,
     backend_args: dict[str, Any] | None,
 ) -> tuple[np.ndarray, int]:
@@ -151,7 +151,7 @@ def read_point_data(
 
 def read_attributes(
     filename: Path | str,
-    comm: MPI.Intracomm,
+    comm: MPI.Comm,
     name: str,
     backend_args: dict[str, Any] | None,
 ) -> dict[str, Any]:
@@ -171,7 +171,7 @@ def read_attributes(
 
 def read_timestamps(
     filename: Path | str,
-    comm: MPI.Intracomm,
+    comm: MPI.Comm,
     function_name: str,
     backend_args: dict[str, Any] | None,
 ) -> npt.NDArray[np.float64 | str]:  # type: ignore[type-var]
@@ -201,7 +201,7 @@ def read_timestamps(
 
 def write_attributes(
     filename: Path | str,
-    comm: MPI.Intracomm,
+    comm: MPI.Comm,
     name: str,
     attributes: dict[str, np.ndarray],
     backend_args: dict[str, Any] | None,
@@ -220,7 +220,7 @@ def write_attributes(
 
 def write_mesh(
     filename: Path | str,
-    comm: MPI.Intracomm,
+    comm: MPI.Comm,
     mesh: MeshData,
     backend_args: dict[str, Any] | None,
     mode: FileMode,
@@ -242,7 +242,7 @@ def write_mesh(
 
 def write_meshtags(
     filename: str | Path,
-    comm: MPI.Intracomm,
+    comm: MPI.Comm,
     data: MeshTagsData,
     backend_args: dict[str, Any] | None,
 ):
@@ -259,7 +259,7 @@ def write_meshtags(
 
 def read_meshtags_data(
     filename: str | Path,
-    comm: MPI.Intracomm,
+    comm: MPI.Comm,
     name: str,
     backend_args: dict[str, Any] | None,
 ) -> MeshTagsData:
@@ -279,7 +279,7 @@ def read_meshtags_data(
 
 def read_dofmap(
     filename: str | Path,
-    comm: MPI.Intracomm,
+    comm: MPI.Comm,
     name: str,
     backend_args: dict[str, Any] | None,
 ) -> dolfinx.graph.AdjacencyList:
@@ -299,7 +299,7 @@ def read_dofmap(
 
 def read_dofs(
     filename: str | Path,
-    comm: MPI.Intracomm,
+    comm: MPI.Comm,
     name: str,
     time: float,
     backend_args: dict[str, Any] | None,
@@ -322,7 +322,7 @@ def read_dofs(
 
 
 def read_cell_perms(
-    comm: MPI.Intracomm, filename: Path | str, backend_args: dict[str, Any] | None
+    comm: MPI.Comm, filename: Path | str, backend_args: dict[str, Any] | None
 ) -> npt.NDArray[np.uint32]:
     """
     Read cell permutation from file with given communicator,
@@ -342,7 +342,7 @@ def read_cell_perms(
 
 def write_function(
     filename: Path,
-    comm: MPI.Intracomm,
+    comm: MPI.Comm,
     u: FunctionData,
     time: float,
     mode: FileMode,
@@ -363,7 +363,7 @@ def write_function(
 
 
 def read_legacy_mesh(
-    filename: Path | str, comm: MPI.Intracomm, group: str
+    filename: Path | str, comm: MPI.Comm, group: str
 ) -> tuple[npt.NDArray[np.int64], npt.NDArray[np.floating], str | None]:
     """Read in the mesh topology, geometry and (optionally) cell type from a
     legacy DOLFIN HDF5-file.
@@ -400,7 +400,7 @@ def snapshot_checkpoint(
 
 
 def read_hdf5_array(
-    comm: MPI.Intracomm,
+    comm: MPI.Comm,
     filename: Path | str,
     group: str,
     backend_args: dict[str, Any] | None,
@@ -423,7 +423,7 @@ def read_hdf5_array(
 
 
 def read_function_names(
-    filename: Path | str, comm: MPI.Intracomm, backend_args: dict[str, Any] | None
+    filename: Path | str, comm: MPI.Comm, backend_args: dict[str, Any] | None
 ) -> list[str]:
     """Read all function names from a file.
 
@@ -455,7 +455,7 @@ def read_function_names(
 def read_cell_data(
     filename: Path | str,
     name: str,
-    comm: MPI.Intracomm,
+    comm: MPI.Comm,
     time: str | float | None,
     backend_args: dict[str, Any] | None,
 ) -> tuple[npt.NDArray[np.int64], np.ndarray]:
@@ -545,7 +545,7 @@ def read_cell_data(
 def write_data(
     filename: Path | str,
     point_data: ArrayData,
-    comm: MPI.Intracomm,
+    comm: MPI.Comm,
     time: str | float | None,
     mode: FileMode,
     backend_args: dict[str, Any] | None,
diff --git a/src/io4dolfinx/checkpointing.py b/src/io4dolfinx/checkpointing.py
index 30d1bd1..a128ef6 100644
--- a/src/io4dolfinx/checkpointing.py
+++ b/src/io4dolfinx/checkpointing.py
@@ -168,6 +168,7 @@ def write_meshtags(
     local_values = meshtags.values[: len(local_tag_entities)]
 
     num_saved_tag_entities = len(local_tag_entities)
+    assert isinstance(mesh.comm, MPI.Intracomm)
     local_start = mesh.comm.exscan(num_saved_tag_entities, op=MPI.SUM)
     local_start = local_start if mesh.comm.rank != 0 else 0
     global_num_tag_entities = mesh.comm.allreduce(num_saved_tag_entities, op=MPI.SUM)
@@ -376,8 +377,9 @@ def read_function(
 
     unique_owners, owner_count = np.unique(owners, return_counts=True)
     # FIXME: In C++ use NBX to find neighbourhood
+    assert isinstance(V.mesh.comm, MPI.Intracomm)
     sub_comm = V.mesh.comm.Create_dist_graph(
-        [V.mesh.comm.rank], [len(unique_owners)], unique_owners, reorder=False
+        [V.mesh.comm.rank], [len(unique_owners)], unique_owners.tolist(), reorder=False
     )
     source, dest, _ = sub_comm.Get_dist_neighbors()
     sub_comm.Free()
@@ -605,7 +607,7 @@ def write_function(
         dofmap_range=dofmap_imap.local_range,
         global_dofs_in_dofmap=dofmap_imap.size_global,
         values=values[:num_dofs_local].copy(),
-        dof_range=local_dof_range,
+        dof_range=(local_dof_range[0], local_dof_range[1]),
         num_dofs_global=num_dofs_global,
         name=name or u.name,
     )
diff --git a/src/io4dolfinx/comm_helpers.py b/src/io4dolfinx/comm_helpers.py
index cf954aa..8a4b62e 100644
--- a/src/io4dolfinx/comm_helpers.py
+++ b/src/io4dolfinx/comm_helpers.py
@@ -29,7 +29,7 @@
 
 
 def send_dofmap_and_recv_values(
-    comm: MPI.Intracomm,
+    comm: MPI.Comm,
     source_ranks: npt.NDArray[np.int32],
     dest_ranks: npt.NDArray[np.int32],
     output_owners: npt.NDArray[np.int32],
@@ -78,6 +78,7 @@ def send_dofmap_and_recv_values(
 
     # Send sizes to create data structures for receiving from NeighAlltoAllv
     recv_size = np.zeros(len(source_ranks), dtype=np.int32)
+    assert isinstance(comm, MPI.Intracomm)
     mesh_to_data_comm = comm.Create_dist_graph_adjacent(
         source_ranks.tolist(), dest_ranks.tolist(), reorder=False
     )
@@ -132,7 +133,7 @@ def send_and_recv_cell_perm(
     cells: npt.NDArray[np.int64],
     perms: npt.NDArray[np.uint32],
     cell_owners: npt.NDArray[np.int32],
-    comm: MPI.Intracomm,
+    comm: MPI.Comm,
 ) -> tuple[npt.NDArray[np.int64], npt.NDArray[np.uint32]]:
     """
     Send global cell index and permutation to corresponding entry in `dest_ranks`.
@@ -146,7 +147,7 @@ def send_and_recv_cell_perm(
     dest_ranks, _dest_size = np.unique(cell_owners, return_counts=True)
     dest_size = _dest_size.astype(np.int32)
     del _dest_size
-
+    assert isinstance(comm, MPI.Intracomm)
     mesh_to_data = comm.Create_dist_graph(
         [comm.rank], [len(dest_ranks)], dest_ranks.tolist(), reorder=False
     )
@@ -189,7 +190,7 @@ def send_and_recv_cell_perm(
 def send_dofs_and_recv_values(
     input_dofmap: npt.NDArray[np.int64],
     dofmap_owners: npt.NDArray[np.int32],
-    comm: MPI.Intracomm,
+    comm: MPI.Comm,
     input_array: npt.NDArray[valid_function_types],
     array_start: int,
 ):
@@ -207,6 +208,7 @@ def send_dofs_and_recv_values(
     dest_size = _dest_size.astype(np.int32)
     del _dest_size
 
+    assert isinstance(comm, MPI.Intracomm)
     dofmap_to_values = comm.Create_dist_graph(
         [comm.rank], [len(dest_ranks)], dest_ranks.tolist(), reorder=False
     )
diff --git a/src/io4dolfinx/original_checkpoint.py b/src/io4dolfinx/original_checkpoint.py
index 45d7e94..fe3631b 100644
--- a/src/io4dolfinx/original_checkpoint.py
+++ b/src/io4dolfinx/original_checkpoint.py
@@ -52,6 +52,7 @@ def create_original_mesh_data(mesh: dolfinx.mesh.Mesh) -> MeshData:
     cell_destinations, _send_cells_per_proc = np.unique(output_cell_owner, return_counts=True)
     send_cells_per_proc = _send_cells_per_proc.astype(np.int32)
     del _send_cells_per_proc
+    assert isinstance(mesh.comm, MPI.Intracomm)
     cell_to_output_comm = mesh.comm.Create_dist_graph(
         [mesh.comm.rank],
         [len(cell_destinations)],
@@ -232,6 +233,7 @@ def create_function_data_on_original_mesh(
     cell_destinations, _send_cells_per_proc = np.unique(output_cell_owner, return_counts=True)
     send_cells_per_proc = _send_cells_per_proc.astype(np.int32)
     del _send_cells_per_proc
+    assert isinstance(mesh.comm, MPI.Intracomm)
     cell_to_output_comm = mesh.comm.Create_dist_graph(
         [mesh.comm.rank],
         [len(cell_destinations)],
@@ -290,6 +292,7 @@ def create_function_data_on_original_mesh(
     # Convert imap index to global index
     imap_global = dofmap.index_map.local_to_global(dmap_loc)
     dofmap_global = (imap_global * index_map_bs + dmap_rem).reshape(unrolled_dofmap.shape)
+    assert len(dofmap_global.shape) >= 2
     num_dofs_per_cell = dofmap_global.shape[1]
     dofmap_insert_position = unroll_insert_position(cell_insert_position, num_dofs_per_cell)
 
diff --git a/src/io4dolfinx/readers.py b/src/io4dolfinx/readers.py
index 0252d8e..0de359a 100644
--- a/src/io4dolfinx/readers.py
+++ b/src/io4dolfinx/readers.py
@@ -60,7 +60,7 @@ def map_dofmap(dofmap: dolfinx.graph.AdjacencyList, bs: int | np.int64) -> npt.N
 
 def send_cells_and_receive_dofmap_index(
     filename: pathlib.Path,
-    comm: MPI.Intracomm,
+    comm: MPI.Comm,
     source_ranks: npt.NDArray[np.int32],
     dest_ranks: npt.NDArray[np.int32],
     dest_size: npt.NDArray[np.int32],
@@ -80,6 +80,7 @@ def send_cells_and_receive_dofmap_index(
     check_file_exists(filename)
 
     recv_size = np.zeros(len(source_ranks), dtype=np.int32)
+    assert isinstance(comm, MPI.Intracomm)
     mesh_to_data_comm = comm.Create_dist_graph_adjacent(
         source_ranks.tolist(), dest_ranks.tolist(), reorder=False
     )
@@ -148,7 +149,7 @@ def send_cells_and_receive_dofmap_index(
 
 def read_mesh_from_legacy_h5(
     filename: pathlib.Path,
-    comm: MPI.Intracomm,
+    comm: MPI.Comm,
     group: str,
     cell_type: str = "tetrahedron",
     backend: str | None = None,
@@ -224,7 +225,7 @@ def read_mesh_from_legacy_h5(
 
 def read_function_from_legacy_h5(
     filename: pathlib.Path,
-    comm: MPI.Intracomm,
+    comm: MPI.Comm,
     u: dolfinx.fem.Function,
     group: str = "mesh",
     step: typing.Optional[int] = None,
@@ -279,8 +280,9 @@ def read_function_from_legacy_h5(
 
     unique_owners, owner_count = np.unique(owners, return_counts=True)
     # FIXME: In C++ use NBX to find neighbourhood
+    assert isinstance(mesh.comm, MPI.Intracomm)
     _tmp_comm = mesh.comm.Create_dist_graph(
-        [mesh.comm.rank], [len(unique_owners)], unique_owners, reorder=False
+        [mesh.comm.rank], [len(unique_owners)], unique_owners.tolist(), reorder=False
     )
     source, dest, _ = _tmp_comm.Get_dist_neighbors()
     _tmp_comm.Free()
diff --git a/src/io4dolfinx/utils.py b/src/io4dolfinx/utils.py
index ef410cd..17731cc 100644
--- a/src/io4dolfinx/utils.py
+++ b/src/io4dolfinx/utils.py
@@ -112,7 +112,7 @@ def unroll_insert_position(
     return unrolled_ip
 
 
-def compute_local_range(comm: MPI.Intracomm, N: int | np.int64):
+def compute_local_range(comm: MPI.Comm, N: int | np.int64):
     """
     Divide a set of `N` objects into `M` partitions, where `M` is
     the size of the MPI communicator `comm`.
@@ -134,7 +134,7 @@ def compute_local_range(comm: MPI.Intracomm, N: int | np.int64):
 
 
 def index_owner(
-    comm: MPI.Intracomm, indices: npt.NDArray[np.int64], N: int | np.int64
+    comm: MPI.Comm, indices: npt.NDArray[np.int64], N: int | np.int64
 ) -> npt.NDArray[np.int32]:
     """
     Find which rank (local to comm) which owns an `index`, given that
diff --git a/src/io4dolfinx/writers.py b/src/io4dolfinx/writers.py
index f7f0cda..67d8131 100644
--- a/src/io4dolfinx/writers.py
+++ b/src/io4dolfinx/writers.py
@@ -117,7 +117,7 @@ def prepare_meshdata_for_storage(mesh: dolfinx.mesh.Mesh, store_partition_info:
 
 def write_mesh(
     filename: Path,
-    comm: MPI.Intracomm,
+    comm: MPI.Comm,
     mesh_data: MeshData,
     time: float = 0.0,
     mode: FileMode = FileMode.write,
@@ -143,7 +143,7 @@ def write_mesh(
 
 def write_function(
     filename: Path,
-    comm: MPI.Intracomm,
+    comm: MPI.Comm,
     u: FunctionData,
     time: float = 0.0,
     mode: FileMode = FileMode.append,