I cannot set a breakpoint on a specific line in a preprocessed fortran file:

[taschna@localhost gdbtest]$ cat main.F
      PROGRAM Test
      IMPLICIT NONE

        WRITE(*,*) 'Hello World'

      END
[taschna@localhost gdbtest]$ gfortran -g -save-temps main.F -o main
[taschna@localhost gdbtest]$ gdb main
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This GDB was configured as "i386-redhat-linux-gnu"...Using host libthread_db
library "/lib/libthread_db.so.1".

(gdb) l
1       # 1 "main.F"
2       # 1 "/home/taschna/gdbtest//"
3       # 1 "<built-in>"
4       # 1 "<command line>"
5       # 1 "main.F"
6             PROGRAM Test
7             IMPLICIT NONE
8
9               WRITE(*,*) 'Hello World'
10
(gdb) b 9
No line 9 in file "main.f".


Using the same file without the preprocessing works fine:

[taschna@localhost gdbtest]$ cp main.F main.f
[taschna@localhost gdbtest]$ gfortran -g -save-temps main.f -o main
[taschna@localhost gdbtest]$ gdb main
.
.
.
(gdb) l
1             PROGRAM Test
2             IMPLICIT NONE
3
4               WRITE(*,*) 'Hello World'
5
6             END
(gdb) b 4
Breakpoint 1 at 0x8048602: file main.f, line 4.