diff --git a/sources/io.F90 b/sources/io.F90
index 32393d7..c91cbfc 100644
--- a/sources/io.F90
+++ b/sources/io.F90
@@ -1594,35 +1594,26 @@ module io
 
     else ! nprocs < lnprocs
 
-! divide files between processes
+! divide files between processes and update the block process accordingly
 !
       nl = 0
-      i  = mod(lnprocs, nprocs)
-      j  = lnprocs / nprocs
-      do p = 0, nprocs
-        k  = 0
-        do n = 0, p
-          nl = k
-          if (n < i) then
-            nu = k + j
-          else
-            nu = k + j - 1
-          end if
-          k = nu + 1
-        end do
-        do n = nl, nu
-          call change_blocks_process(n, p)
-        end do
-      end do
-      k  = 0
-      do n = 0, nproc
-        nl = k
-        if (n < i) then
-          nu = k + j
+      nd = lnprocs / nprocs
+      nr = mod(lnprocs, nprocs)
+      do n = 0, nprocs - 1
+        if (n < nr) then
+          il = n * (nd + 1)
+          iu = il + nd
         else
-          nu = k + j - 1
+          il = n * nd + nr
+          iu = il + nd - 1
+        end if
+        do i = il, iu
+          call change_blocks_process(i, n)
+        end do
+        if (n == nproc) then
+          nl = il
+          nu = iu
         end if
-        k = nu + 1
       end do
 
       do n = nl, nu