diff --git a/src/framework/MOM_checksums.F90 b/src/framework/MOM_checksums.F90
index 26ee96b399..b6f2a1c334 100644
--- a/src/framework/MOM_checksums.F90
+++ b/src/framework/MOM_checksums.F90
@@ -1155,14 +1155,14 @@ end subroutine chksum_u_3d
 !---chksum_general interface routines
 !> Return the bitcount of an arbitrarily sized 3d array
 integer function chksum_general_3d( array, scale_factor, istart, iend, jstart, jend, kstart, kend ) result(subchk)
-  real, dimension(:,:,:) :: array    !< Array to be checksummed
-  real,    optional :: scale_factor  !< Factor to scale array by before checksum
-  integer, optional :: istart        !< Starting index in the i-direction
-  integer, optional :: iend          !< Ending index in the i-direction
-  integer, optional :: jstart        !< Starting index in the j-direction
-  integer, optional :: jend          !< Ending index in the j-direction
-  integer, optional :: kstart        !< Starting index in the k-direction
-  integer, optional :: kend          !< Ending index in the k-direction
+  real, dimension(:,:,:), intent(in) :: array    !< Array to be checksummed
+  real,    optional, intent(in) :: scale_factor  !< Factor to scale array by before checksum
+  integer, optional, intent(in) :: istart        !< Starting index in the i-direction
+  integer, optional, intent(in) :: iend          !< Ending index in the i-direction
+  integer, optional, intent(in) :: jstart        !< Starting index in the j-direction
+  integer, optional, intent(in) :: jend          !< Ending index in the j-direction
+  integer, optional, intent(in) :: kstart        !< Starting index in the k-direction
+  integer, optional, intent(in) :: kend          !< Ending index in the k-direction
   integer :: i, j, k, bc, is, ie, js, je, ks, ke
   real :: scale
 
@@ -1192,11 +1192,11 @@ end function chksum_general_3d
 !> Return the bitcount of an arbitrarily sized 2d array by promotion to a 3d array
 integer function chksum_general_2d( array_2d, scale_factor, istart, iend, jstart, jend )
   real, dimension(:,:) :: array_2d   !< Array to be checksummed
-  real,    optional :: scale_factor  !< Factor to scale array by before checksum
-  integer, optional :: istart        !< Starting index in the i-direction
-  integer, optional :: iend          !< Ending index in the i-direction
-  integer, optional :: jstart        !< Starting index in the j-direction
-  integer, optional :: jend          !< Ending index in the j-direction
+  real,    optional, intent(in) :: scale_factor  !< Factor to scale array by before checksum
+  integer, optional, intent(in) :: istart        !< Starting index in the i-direction
+  integer, optional, intent(in) :: iend          !< Ending index in the i-direction
+  integer, optional, intent(in) :: jstart        !< Starting index in the j-direction
+  integer, optional, intent(in) :: jend          !< Ending index in the j-direction
   integer :: is, ie, js, je
   real, dimension(:,:,:), allocatable :: array_3d !< Promotion from 2d to 3d array
 
@@ -1512,8 +1512,8 @@ end function is_NaN_0d
 !> This function returns .true. if any element of x is a NaN, and .false. otherwise.
 function is_NaN_1d(x, skip_mpp)
   real, dimension(:), intent(in) :: x !< The array to be checked for NaNs.
+  logical,  optional, intent(in) :: skip_mpp  !< If true, only check this array only on the local PE (default false).
   logical :: is_NaN_1d
-  logical, optional :: skip_mpp  !< If true, only check this array only on the local PE (default false).
 
   integer :: i, n
   logical :: call_mpp