diff --git a/Overlap/write_overlap.f90 b/Overlap/write_overlap.f90
index 25a5bd449c3ba93c3e611ecd88cc38c1d97fe35f..da9fada0e48b8114f5c45236daf07d6d32f93102 100644
--- a/Overlap/write_overlap.f90
+++ b/Overlap/write_overlap.f90
@@ -9,11 +9,11 @@ module write_overlap_m
 
 contains
 
-  subroutine write_overlap(hshp_interp, k, delta, i1, i2, m, i_interp, &
+  subroutine write_overlap(hshp_interp, d, delta, i1, i2, m, i_interp, &
        cyclone, coord_extr_1, ssh_extr_1, coord_extr_2, ssh_extr_2, w)
 
     ! Writes edges to unit_edge and interpolated eddies to shapefiles,
-    ! between (k - delta, i1) and (k, i2).
+    ! between (d - delta, i1) and (d, i2).
 
     ! Libraries:
     use nr_util, only: twopi
@@ -23,7 +23,7 @@ contains
     use write_eddy_m, only: write_eddy
 
     TYPE(shpc), intent(in):: hshp_interp
-    integer, intent(in):: k ! date index
+    integer, intent(in):: d ! date, in days since 1950-1-1
     integer, intent(in):: delta, i1, i2, m
     integer, intent(in):: i_interp(:) ! (delta - 1)
     logical, intent(in):: cyclone
@@ -37,7 +37,7 @@ contains
     real, intent(in):: w
 
     ! Local:
-    integer i_pred, j_interp, k_interp
+    integer i_pred, j_interp, d_interp
     real w_interp
     real coord_extr_2_local(2)
 
@@ -63,14 +63,14 @@ contains
             + w_interp * coord_extr_2_local
        e%ssh_extr = (1 - w_interp) * ssh_extr_1 + w_interp * ssh_extr_2
 
-       k_interp = k - delta + j_interp
-       call write_eddy(e, hshp_interp, k_interp, i_interp(j_interp))
-       write(unit_edge, fmt = *) k_interp - 1, i_pred, k_interp, &
+       d_interp = d - delta + j_interp
+       call write_eddy(e, hshp_interp, d_interp, i_interp(j_interp))
+       write(unit_edge, fmt = *) d_interp - 1, i_pred, d_interp, &
             i_interp(j_interp), w
        i_pred = i_interp(j_interp)
     end do
 
-    write(unit_edge, fmt = *) k - 1, i_pred, k, i2, w
+    write(unit_edge, fmt = *) d - 1, i_pred, d, i2, w
 
   end subroutine write_overlap