diff --git a/src/offline/cable_driver_common.F90 b/src/offline/cable_driver_common.F90
index c76336a7a..a8ad98b58 100644
--- a/src/offline/cable_driver_common.F90
+++ b/src/offline/cable_driver_common.F90
@@ -113,7 +113,7 @@ MODULE cable_driver_common_mod
   SUBROUTINE cable_driver_init(mpi_grp, trunk_sumbal, NRRRR)
     !! Model initialisation routine for the CABLE offline driver.
     TYPE(mpi_grp_t), INTENT(IN) :: mpi_grp !! MPI group to use
-    DOUBLE PRECISION, INTENT(OUT) :: trunk_sumbal
+    DOUBLE PRECISION, ALLOCATABLE, INTENT(OUT) :: trunk_sumbal
       !! Reference value for quasi-bitwise reproducibility checks.
     INTEGER, INTENT(OUT) :: NRRRR !! Number of repeated spin-up cycles
 
@@ -141,6 +141,7 @@ SUBROUTINE cable_driver_init(mpi_grp, trunk_sumbal, NRRRR)
     IF (mpi_grp%rank == 0 .AND. cable_user%consistency_check) THEN
       OPEN(NEWUNIT=unit, FILE=filename%trunk_sumbal, STATUS='old', ACTION='READ', IOSTAT=ioerror)
       IF(ioerror == 0) THEN
+        ALLOCATE(trunk_sumbal)
         READ(unit, *) trunk_sumbal  ! written by previous trunk version
       END IF
       CLOSE(unit)
diff --git a/src/offline/cable_mpimaster.F90 b/src/offline/cable_mpimaster.F90
index 00be9085b..6c51099ff 100644
--- a/src/offline/cable_mpimaster.F90
+++ b/src/offline/cable_mpimaster.F90
@@ -227,7 +227,7 @@ SUBROUTINE mpidrv_master (comm, trunk_sumbal, dels, koffset, kend, PLUME, CRU)
 
     ! MPI:
     INTEGER               :: comm ! MPI communicator for comms with the workers
-    DOUBLE PRECISION, INTENT(IN) :: trunk_sumbal
+    DOUBLE PRECISION, ALLOCATABLE, INTENT(IN) :: trunk_sumbal
       !! Reference value for quasi-bitwise reproducibility checks.
     REAL, INTENT(INOUT) :: dels !! Time step size in seconds
     INTEGER, INTENT(INOUT) :: koffset !! Timestep to start at
@@ -315,6 +315,7 @@ SUBROUTINE mpidrv_master (comm, trunk_sumbal, dels, koffset, kend, PLUME, CRU)
 
     INTEGER :: count_bal = 0
     INTEGER :: nkend=0
+    INTEGER :: unit
 
     INTEGER :: kk,m,np,ivt
     INTEGER, PARAMETER :: mloop = 30   ! CASA-CNP PreSpinup loops
@@ -900,7 +901,7 @@ SUBROUTINE mpidrv_master (comm, trunk_sumbal, dels, koffset, kend, PLUME, CRU)
             IF(ktau==(kend-1)) THEN
 
               nkend = nkend+1
-              IF( ABS(new_sumbal-trunk_sumbal) < 1.e-7) THEN
+              IF(ALLOCATED(trunk_sumbal) .AND. ABS(new_sumbal-trunk_sumbal) < 1.e-7) THEN
 
                 PRINT *, ""
                 PRINT *, &
@@ -915,13 +916,12 @@ SUBROUTINE mpidrv_master (comm, trunk_sumbal, dels, koffset, kend, PLUME, CRU)
                       "NB. Offline-parallel runs spinup cycles:", nkend
                 PRINT *, &
                       "Internal check shows in this version new_sumbal != trunk sumbal"
-                PRINT *, "The difference is: ", new_sumbal - trunk_sumbal
                 PRINT *, &
                       "Writing new_sumbal to the file:", TRIM(filename%new_sumbal)
 
-                !CLN                      OPEN( 12, FILE = filename%new_sumbal )
-                !CLN                      WRITE( 12, '(F20.7)' ) new_sumbal  ! written by previous trunk version
-                !CLN                      CLOSE(12)
+                OPEN(newunit=unit, file=filename%new_sumbal)
+                WRITE(unit, '(F20.7)') new_sumbal  ! written by previous trunk version
+                CLOSE(unit)
 
               ENDIF
 
diff --git a/src/offline/cable_offline_driver.F90 b/src/offline/cable_offline_driver.F90
index d5e5d0f5f..b1497413a 100644
--- a/src/offline/cable_offline_driver.F90
+++ b/src/offline/cable_offline_driver.F90
@@ -23,7 +23,7 @@ PROGRAM cable_offline_driver
 
   REAL    :: etime ! Declare the type of etime()
   TYPE(mpi_grp_t) :: mpi_grp
-  DOUBLE PRECISION :: trunk_sumbal
+  DOUBLE PRECISION, ALLOCATABLE :: trunk_sumbal
     !! Reference value for quasi-bitwise reproducibility checks.
   INTEGER :: NRRRR !! Number of repeated spin-up cycles
   REAL :: dels !! Time step size in seconds
diff --git a/src/offline/cable_serial.F90 b/src/offline/cable_serial.F90
index 90e27e5fb..2b3b4559d 100644
--- a/src/offline/cable_serial.F90
+++ b/src/offline/cable_serial.F90
@@ -158,7 +158,7 @@ MODULE cable_serial
 
 SUBROUTINE serialdrv(trunk_sumbal, NRRRR, dels, koffset, kend, GSWP_MID, PLUME, CRU, site)
   !! Offline serial driver.
-  DOUBLE PRECISION, INTENT(IN) :: trunk_sumbal
+  DOUBLE PRECISION, ALLOCATABLE, INTENT(IN) :: trunk_sumbal
     !! Reference value for quasi-bitwise reproducibility checks.
   INTEGER, INTENT(IN) :: NRRRR !! Number of repeated spin-up cycles
   REAL, INTENT(INOUT) :: dels !! Time step size in seconds
@@ -258,6 +258,7 @@ SUBROUTINE serialdrv(trunk_sumbal, NRRRR, dels, koffset, kend, GSWP_MID, PLUME,
 
   INTEGER :: nkend=0
   INTEGER :: count_bal = 0
+  INTEGER :: unit
 
   ! for landuse
   integer     mlon,mlat, mpx
@@ -766,7 +767,7 @@ SUBROUTINE serialdrv(trunk_sumbal, NRRRR, dels, koffset, kend, GSWP_MID, PLUME,
             IF( ktau == kend ) THEN
               nkend = nkend+1
 
-              IF( ABS(new_sumbal-trunk_sumbal) < 1.e-7) THEN
+              IF(ALLOCATED(trunk_sumbal) .AND. ABS(new_sumbal-trunk_sumbal) < 1.e-7) THEN
 
                 PRINT *, ""
                 PRINT *, &
@@ -784,9 +785,9 @@ SUBROUTINE serialdrv(trunk_sumbal, NRRRR, dels, koffset, kend, GSWP_MID, PLUME,
                 PRINT *, &
                      "Writing new_sumbal to the file:", TRIM(filename%new_sumbal)
 
-                OPEN( 12, FILE = filename%new_sumbal )
-                WRITE( 12, '(F20.7)' ) new_sumbal  ! written by previous trunk version
-                CLOSE(12)
+                OPEN(newunit=unit, file=filename%new_sumbal)
+                WRITE(unit, '(F20.7)') new_sumbal  ! written by previous trunk version
+                CLOSE(unit)
 
               ENDIF
             ENDIF