diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index df9d597793c..b23124664e3 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2010-03-29  Tobias Burnus  <burnus@net-b.de>
+
+	PR fortran/43551
+	* gfortran.dg/direct_io_12.f90: New test.
+
 2010-03-28  Jan Hubicka  <jh@suse.cz>
 
 	PR tree-optimization/43505
diff --git a/gcc/testsuite/gfortran.dg/direct_io_12.f90 b/gcc/testsuite/gfortran.dg/direct_io_12.f90
new file mode 100644
index 00000000000..53367027242
--- /dev/null
+++ b/gcc/testsuite/gfortran.dg/direct_io_12.f90
@@ -0,0 +1,33 @@
+! { dg-do run }
+! 
+! PR fortran/43551
+!
+! Writes a 672000 byte file with buffering. The writing failed because
+! of a missing lseek.
+
+implicit none
+integer, parameter :: size = 2800 ! << needs to be large enough
+real(8) :: vec1(size,30), dummy(size)
+integer i
+
+CALL RANDOM_NUMBER(vec1)
+
+open(99, file='test.dat', form='unformatted', access='direct', recl=size*8)
+do i = 1, 10
+  write(99,rec=i) vec1(:,i)
+  write(99,rec=i+10) vec1(:,i+10)
+  write(99,rec=i+20) vec1(:,i+20) ! << rec = 30 was written to rec = 21
+end do
+
+do i = 1, 10
+  read(99,rec=i) dummy
+  if (any (dummy /= vec1(:,i))) call abort()
+  read(99,rec=i+10) dummy
+  if (any (dummy /= vec1(:,i+10))) call abort()
+  read(99,rec=i+20) dummy
+  if (any (dummy /= vec1(:,i+20))) call abort() ! << aborted here for rec = 21
+end do
+
+close(99, status='delete')
+end
+
diff --git a/libgfortran/ChangeLog b/libgfortran/ChangeLog
index b13f107f736..4958831010e 100644
--- a/libgfortran/ChangeLog
+++ b/libgfortran/ChangeLog
@@ -1,3 +1,8 @@
+2010-03-29  Tobias Burnus  <burnus@net-b.de>
+
+	PR fortran/43551
+	* io/unix.c (buf_write): Set physical_offset after lseek.
+
 2010-03-25  Jerry DeLisle  <jvdelisle@gcc.gnu.org>
 
 	PR libfortran/43517
diff --git a/libgfortran/io/unix.c b/libgfortran/io/unix.c
index 4435674b46d..ea3b8bc4b40 100644
--- a/libgfortran/io/unix.c
+++ b/libgfortran/io/unix.c
@@ -496,13 +496,17 @@ buf_write (unix_stream * s, const void * buf, ssize_t nbyte)
           s->ndirty += nbyte;
         }
       else
-        {
-          if (s->file_length != -1 && s->physical_offset != s->logical_offset
-              && lseek (s->fd, s->logical_offset, SEEK_SET) < 0)
-            return -1;
-          nbyte = raw_write (s, buf, nbyte);
-          s->physical_offset += nbyte;
-        }
+	{
+	  if (s->file_length != -1 && s->physical_offset != s->logical_offset)
+	    {
+	      if (lseek (s->fd, s->logical_offset, SEEK_SET) < 0)
+		return -1;
+	      s->physical_offset = s->logical_offset;
+	    }
+
+	  nbyte = raw_write (s, buf, nbyte);
+	  s->physical_offset += nbyte;
+	}
     }
   s->logical_offset += nbyte;
   /* Don't increment file_length if the file is non-seekable.  */