diff --git a/lib/mpifx_constants.fpp b/lib/mpifx_constants.fpp
index 2266e01..48ff532 100644
--- a/lib/mpifx_constants.fpp
+++ b/lib/mpifx_constants.fpp
@@ -10,7 +10,7 @@ module mpifx_constants_module
   public :: MPI_MODE_NOSTORE, MPI_MODE_NOPUT, MPI_MODE_NOPRECEDE, MPI_MODE_NOSUCCEED
   public :: MPI_THREAD_SINGLE, MPI_THREAD_FUNNELED, MPI_THREAD_SERIALIZED, MPI_THREAD_MULTIPLE
   public :: MPI_COMM_TYPE_SHARED
-  public :: MPIFX_UNHANDLED_ERROR, MPIFX_ASSERT_FAILED
+  public :: MPIFX_UNHANDLED_ERROR, MPIFX_ASSERT_FAILED, MPIFX_SIZE_T
 
 
   !> Exit code for errors which were not caught due to missing optional arguments
@@ -19,6 +19,8 @@ module mpifx_constants_module
   !> Exit code for failed assertions
   integer, parameter :: MPIFX_ASSERT_FAILED = 2
 
+  integer, parameter :: MPIFX_SIZE_T = MPI_ADDRESS_KIND
+
 end module mpifx_constants_module
 
 !> \endcond
diff --git a/lib/mpifx_win.fpp b/lib/mpifx_win.fpp
index f36eaf2..ef0c9f4 100644
--- a/lib/mpifx_win.fpp
+++ b/lib/mpifx_win.fpp
@@ -1,9 +1,11 @@
 #:include 'mpifx.fypp'
 #:set TYPES = NUMERIC_TYPES
+#:set INT_TYPES = ['int32', 'int64']
 
 !> Contains routined for MPI shared memory windows.
 module mpifx_win_module
   use mpifx_common_module
+  use mpifx_constants_module, only : MPIFX_SIZE_T
   use iso_c_binding, only : c_ptr, c_f_pointer
   implicit none
   private
@@ -18,11 +20,15 @@ module mpifx_win_module
   contains
     !> Initializes an MPI shared memory window.
   #:for TYPE in TYPES
-    generic :: allocate_shared => mpifx_win_allocate_shared_${TYPE_ABBREVS[TYPE]}$
+    #:for INT_TYPE in INT_TYPES
+      generic :: allocate_shared => mpifx_win_allocate_shared_${TYPE_ABBREVS[TYPE]}$_${INT_TYPE}$
+    #:endfor
   #:endfor
 
   #:for TYPE in TYPES
-    procedure, private :: mpifx_win_allocate_shared_${TYPE_ABBREVS[TYPE]}$
+    #:for INT_TYPE in INT_TYPES
+      procedure, private :: mpifx_win_allocate_shared_${TYPE_ABBREVS[TYPE]}$_${INT_TYPE}$
+    #:endfor
   #:endfor
 
     !> Locks a shared memory segment for remote access.
@@ -44,7 +50,7 @@ module mpifx_win_module
 
 contains
 
-#:def mpifx_win_allocate_shared_template(SUFFIX, TYPE)
+#:def mpifx_win_allocate_shared_template(SUFFIX, TYPE, ADDRESS_KIND)
 
   !> Initialized a window handle and returns a pointer to the address associated with a shared
   !> memory segment.
@@ -64,9 +70,9 @@ contains
       & local_length, local_pointer, error)
     class(mpifx_win), intent(out) :: self
     class(mpifx_comm), intent(in) :: mycomm
-    integer, intent(in) :: global_length
+    integer${ADDRESS_KIND}$, intent(in) :: global_length
     ${TYPE}$, pointer, intent(out) :: global_pointer(:)
-    integer, intent(in), optional :: local_length
+    integer${ADDRESS_KIND}$, intent(in), optional :: local_length
     ${TYPE}$, pointer, intent(out), optional :: local_pointer(:)
     integer, intent(out), optional :: error
 
@@ -211,9 +217,11 @@ contains
 
 #:for TYPE in TYPES
   #:set FTYPE = FORTRAN_TYPES[TYPE]
-  #:set SUFFIX = TYPE_ABBREVS[TYPE]
 
-  $:mpifx_win_allocate_shared_template(SUFFIX, FTYPE)
+  #:for ADDRESS_KIND, INT_TYPE in zip(['', '(MPIFX_SIZE_T)'], INT_TYPES)
+    #:set SUFFIX = TYPE_ABBREVS[TYPE] + '_' + INT_TYPE
+    $:mpifx_win_allocate_shared_template(SUFFIX, FTYPE, ADDRESS_KIND)
+  #:endfor
 
 #:endfor
 
diff --git a/test/test_win_shared_mem.f90 b/test/test_win_shared_mem.f90
index fbad591..ead4583 100644
--- a/test/test_win_shared_mem.f90
+++ b/test/test_win_shared_mem.f90
@@ -5,7 +5,9 @@ program test_win_shared_mem
   type(mpifx_comm) :: globalcomm, nodecomm
   type(mpifx_win) :: win
   integer, parameter :: sample_value = 42, size_rank_0 = 7, size_rank_other = 4
-  integer :: global_length, local_length, rank, ii
+  integer(MPIFX_SIZE_T) :: global_length, local_length
+  integer :: global_length_int32, local_length_int32
+  integer :: rank, ii
   integer, pointer :: global_pointer(:), local_pointer(:)
 
   call mpifx_init()
@@ -77,6 +79,13 @@ program test_win_shared_mem
     end if
   end do
 
+  call win%free()
+
+  ! Initialize again with int32 sizes
+  global_length_int32 = global_length
+  local_length_int32 = local_length
+  call win%allocate_shared(nodecomm, global_length_int32, global_pointer, local_length_int32, local_pointer)
+
   call win%free()
   call mpifx_finalize()