diff --git a/src/finalize_global_grid.jl b/src/finalize_global_grid.jl
index 3c3ffb7..a39e47d 100644
--- a/src/finalize_global_grid.jl
+++ b/src/finalize_global_grid.jl
@@ -11,11 +11,11 @@ Finalize the global grid (and also MPI by default).
 
 # Arguments
 !!! note "Advanced keyword arguments"
-    - `finalize_MPI::Bool=true`: whether to finalize MPI (`true`) or not (`false`).
+    - `finalize_MPI::Bool=(MPI.Initialized() && !MPI.Finalized())`: whether to finalize MPI (`true`) or not (`false`).
 
 See also: [`init_global_grid`](@ref)
 """
-function finalize_global_grid(;finalize_MPI::Bool=true)
+function finalize_global_grid(;finalize_MPI::Bool=(MPI.Initialized() && !MPI.Finalized()))
     check_initialized();
     free_gather_buffer();
     free_update_halo_buffers();
diff --git a/src/init_global_grid.jl b/src/init_global_grid.jl
index 2224131..40c960e 100644
--- a/src/init_global_grid.jl
+++ b/src/init_global_grid.jl
@@ -19,7 +19,7 @@ Initialize a Cartesian grid of MPI processes (and also MPI itself by default) de
     - `disp::Integer=1`:  the displacement argument to `MPI.Cart_shift` in order to determine the neighbors.
     - `reorder::Integer=1`: the reorder argument to `MPI.Cart_create` in order to create the Cartesian process topology.
     - `comm::MPI.Comm=MPI.COMM_WORLD`: the input communicator argument to `MPI.Cart_create` in order to create the Cartesian process topology.
-    - `init_MPI::Bool=true`: whether to initialize MPI (`true`) or not (`false`).
+    - `init_MPI::Bool=!MPI.Initialized()`: whether to initialize MPI (`true`) or not (`false`).
     - `select_device::Bool=true`: whether to automatically select the device (GPU) (`true`) or not (`false`) if CUDA is functional. If `true`, it selects the device corresponding to the node-local MPI rank. This method of device selection suits both single and multi-device compute nodes and is recommended in general. It is also the default method of device selection of the *function* [`select_device`](@ref).
     For more information, refer to the documentation of MPI.jl / MPI.
 
@@ -39,7 +39,7 @@ Initialize a Cartesian grid of MPI processes (and also MPI itself by default) de
 
 See also: [`finalize_global_grid`](@ref), [`select_device`](@ref)
 """
-function init_global_grid(nx::Integer, ny::Integer, nz::Integer; dimx::Integer=0, dimy::Integer=0, dimz::Integer=0, periodx::Integer=0, periody::Integer=0, periodz::Integer=0, overlapx::Integer=2, overlapy::Integer=2, overlapz::Integer=2, disp::Integer=1, reorder::Integer=1, comm::MPI.Comm=MPI.COMM_WORLD, init_MPI::Bool=true, select_device::Bool=true, quiet::Bool=false)
+function init_global_grid(nx::Integer, ny::Integer, nz::Integer; dimx::Integer=0, dimy::Integer=0, dimz::Integer=0, periodx::Integer=0, periody::Integer=0, periodz::Integer=0, overlapx::Integer=2, overlapy::Integer=2, overlapz::Integer=2, disp::Integer=1, reorder::Integer=1, comm::MPI.Comm=MPI.COMM_WORLD, init_MPI::Bool=!MPI.Initialized(), select_device::Bool=true, quiet::Bool=false)
     if grid_is_initialized() error("The global grid has already been initialized.") end
     nxyz              = [nx, ny, nz];
     dims              = [dimx, dimy, dimz];