diff --git a/field_RANKSUFF_data_module.fypp b/field_RANKSUFF_data_module.fypp
index 7a5d7ec..5663023 100644
--- a/field_RANKSUFF_data_module.fypp
+++ b/field_RANKSUFF_data_module.fypp
@@ -110,11 +110,12 @@ CONTAINS
 #ifdef _OPENACC
   USE OPENACC
 #endif
+  USE, INTRINSIC :: ISO_FORTRAN_ENV, ONLY : INT64 
     ${ft.type}$, POINTER :: HST (${ft.shape}$), DEV (${ft.shape}$)
     LOGICAL,                       INTENT (IN) :: MAP_DEVPTR
     INTEGER (KIND=JPIM),           INTENT (IN) :: KDIR
     INTEGER (KIND=JPIM), OPTIONAL, INTENT (IN) :: QUEUE
-    INTEGER (KIND=JPIM) :: ISIZE
+    INTEGER (KIND=INT64)                       :: ISIZE
     INTEGER :: ${', '.join (['J'] + list (map (lambda i: 'J' + str (i+1), range (d, ft.rank))))}$
 #ifdef _OPENACC
     TYPE(C_DEVPTR) :: DEVPTR
@@ -139,7 +140,7 @@ CONTAINS
     #:if d == 0
     ${indent}$  ISIZE = KIND (HST)
     #:else
-    ${indent}$  ISIZE = KIND (HST) * SIZE (HST (${ar}$))
+    ${indent}$  ISIZE = SIZEOF (HST)
     #:endif
     ${indent}$  IF (KDIR == NH2D) THEN
 #ifdef _OPENACC