diff --git a/assimilation_code/modules/utilities/win_mod.f90 b/assimilation_code/modules/utilities/win_mod.f90
index e96526100..2c424482b 100644
--- a/assimilation_code/modules/utilities/win_mod.f90
+++ b/assimilation_code/modules/utilities/win_mod.f90
@@ -57,7 +57,7 @@ subroutine create_state_window(state_ens_handle, fwd_op_ens_handle, qc_ens_handl
 
 integer :: ierr
 integer :: bytesize !< size in bytes of each element in the window
-integer :: my_num_vars !< my number of vars
+integer(i8) :: my_num_vars !< my number of vars
 
 ! Find out how many copies to get, maybe different to state_ens_handle%num_copies
 data_count = copies_in_window(state_ens_handle)
@@ -97,7 +97,7 @@ subroutine create_mean_window(state_ens_handle, mean_copy, distribute_mean)
 
 integer               :: ierr
 integer               :: bytesize
-integer               :: my_num_vars !< number of elements a task owns
+integer(i8)           :: my_num_vars !< number of elements a task owns
 
 ! create an ensemble handle of just the mean copy.
 use_distributed_mean = distribute_mean
diff --git a/assimilation_code/modules/utilities/winf08_mod.f90 b/assimilation_code/modules/utilities/winf08_mod.f90
index 54f14de3d..956462445 100644
--- a/assimilation_code/modules/utilities/winf08_mod.f90
+++ b/assimilation_code/modules/utilities/winf08_mod.f90
@@ -57,7 +57,7 @@ subroutine create_state_window(state_ens_handle, fwd_op_ens_handle, qc_ens_handl
 
 integer :: ierr
 integer :: bytesize !< size in bytes of each element in the window
-integer :: my_num_vars !< my number of vars
+integer(i8) :: my_num_vars !< my number of vars
 
 ! Find out how many copies to get, maybe different to state_ens_handle%num_copies
 data_count = copies_in_window(state_ens_handle)
@@ -97,7 +97,7 @@ subroutine create_mean_window(state_ens_handle, mean_copy, distribute_mean)
 
 integer               :: ierr
 integer               :: bytesize
-integer               :: my_num_vars !< number of elements a task owns
+integer(i8)           :: my_num_vars !< number of elements a task owns
 
 ! create an ensemble handle of just the mean copy.
 use_distributed_mean = distribute_mean