diff --git a/libio/fileops.c b/libio/fileops.c
index 2e7bc8d..cf68dbf 100644
--- a/libio/fileops.c
+++ b/libio/fileops.c
@@ -232,13 +232,18 @@ _IO_file_open (fp, filename, posix_mode, prot, read_write, is32not64)
     return NULL;
   fp->_fileno = fdesc;
   _IO_mask_flags (fp, read_write,_IO_NO_READS+_IO_NO_WRITES+_IO_IS_APPENDING);
-  if ((read_write & _IO_IS_APPENDING) && (read_write & _IO_NO_READS))
-    if (_IO_SEEKOFF (fp, (_IO_off64_t)0, _IO_seek_end, _IOS_INPUT|_IOS_OUTPUT)
-	== _IO_pos_BAD && errno != ESPIPE)
-      {
-	close_not_cancel (fdesc);
-	return NULL;
-      }
+  /* For append mode, send the file offset to the end of the file.  Don't
+     update the offset cache though, since the file handle is not active.  */
+  if ((read_write & (_IO_IS_APPENDING | _IO_NO_READS))
+      == (_IO_IS_APPENDING | _IO_NO_READS))
+    {
+      _IO_off64_t new_pos = _IO_SYSSEEK (fp, 0, _IO_seek_end);
+      if (new_pos == _IO_pos_BAD && errno != ESPIPE)
+	{
+	  close_not_cancel (fdesc);
+	  return NULL;
+	}
+    }
   _IO_link_in ((struct _IO_FILE_plus *) fp);
   return fp;
 }
@@ -929,43 +934,13 @@ _IO_file_sync_mmap (_IO_FILE *fp)
   return 0;
 }
 
-/* Get the current file offset using a system call.  This is the safest method
-   to get the current file offset, since we are sure that we get the current
-   state of the file.  Before the stream handle is activated (by using fread,
-   fwrite, etc.), an application may alter the state of the file descriptor
-   underlying it by calling read/write/lseek on it.  Using a cached offset at
-   this point will result in returning the incorrect value.  Same is the case
-   when one switches from reading in a+ mode to writing, where the buffer has
-   not been flushed - the cached offset would reflect the reading position
-   while the actual write position would be at the end of the file.
-
-   do_ftell and do_ftell_wide may resort to using the cached offset in some
-   special cases instead of calling get_file_offset, but those cases should be
-   thoroughly described.  */
-_IO_off64_t
-get_file_offset (_IO_FILE *fp)
-{
-  if ((fp->_flags & _IO_IS_APPENDING) == _IO_IS_APPENDING)
-    {
-      struct stat64 st;
-      bool ret = (_IO_SYSSTAT (fp, &st) == 0 && S_ISREG (st.st_mode));
-      if (ret)
-	return st.st_size;
-      else
-	return EOF;
-    }
-  else
-    return _IO_SYSSEEK (fp, 0, _IO_seek_cur);
-}
-
-
-/* ftell{,o} implementation.  Don't modify any state of the file pointer while
-   we try to get the current state of the stream.  */
+/* ftell{,o} implementation.  The only time we modify the state of the stream
+   is when we have unflushed writes.  In that case we seek to the end and
+   record that offset in the stream object.  */
 static _IO_off64_t
 do_ftell (_IO_FILE *fp)
 {
-  _IO_off64_t result = 0;
-  bool use_cached_offset = false;
+  _IO_off64_t result, offset = 0;
 
   /* No point looking at unflushed data if we haven't allocated buffers
      yet.  */
@@ -974,39 +949,37 @@ do_ftell (_IO_FILE *fp)
       bool was_writing = (fp->_IO_write_ptr > fp->_IO_write_base
 			  || _IO_in_put_mode (fp));
 
+      bool append_mode = (fp->_flags & _IO_IS_APPENDING) == _IO_IS_APPENDING;
+
+      /* When we have unflushed writes in append mode, seek to the end of the
+	 file and record that offset.  This is the only time we change the file
+	 stream state and it is safe since the file handle is active.  */
+      if (was_writing && append_mode)
+	{
+	  result = _IO_SYSSEEK (fp, 0, _IO_seek_end);
+	  if (result == _IO_pos_BAD)
+	    return EOF;
+	  else
+	    fp->_offset = result;
+	}
+
       /* Adjust for unflushed data.  */
       if (!was_writing)
-	result -= fp->_IO_read_end - fp->_IO_read_ptr;
+	offset -= fp->_IO_read_end - fp->_IO_read_ptr;
       else
-	result += fp->_IO_write_ptr - fp->_IO_read_end;
-
-      /* It is safe to use the cached offset when available if there is
-	 unbuffered data (indicating that the file handle is active) and the
-	 handle is not for a file open in a+ mode.  The latter condition is
-	 because there could be a scenario where there is a switch from read
-	 mode to write mode using an fseek to an arbitrary position.  In this
-	 case, there would be unbuffered data due to be appended to the end of
-	 the file, but the offset may not necessarily be the end of the
-	 file.  It is fine to use the cached offset when the a+ stream is in
-	 read mode though, since the offset is maintained correctly in that
-	 case.  Note that this is not a comprehensive set of cases when the
-	 offset is reliable.  The offset may be reliable even in some cases
-	 where there is no unflushed input and the handle is active, but it's
-	 just that we don't have a way to identify that condition reliably.  */
-      use_cached_offset = (result != 0 && fp->_offset != _IO_pos_BAD
-			   && ((fp->_flags & (_IO_IS_APPENDING | _IO_NO_READS))
-			       == (_IO_IS_APPENDING | _IO_NO_READS)
-			       && was_writing));
+	offset += fp->_IO_write_ptr - fp->_IO_read_end;
     }
 
-  if (use_cached_offset)
-    result += fp->_offset;
+  if (fp->_offset != _IO_pos_BAD)
+    result = fp->_offset;
   else
-    result += get_file_offset (fp);
+    result = _IO_SYSSEEK (fp, 0, _IO_seek_cur);
 
   if (result == EOF)
     return result;
 
+  result += offset;
+
   if (result < 0)
     {
       __set_errno (EINVAL);
@@ -1016,7 +989,6 @@ do_ftell (_IO_FILE *fp)
   return result;
 }
 
-
 _IO_off64_t
 _IO_new_file_seekoff (fp, offset, dir, mode)
      _IO_FILE *fp;
diff --git a/libio/iofdopen.c b/libio/iofdopen.c
index 3f266f7..364e175 100644
--- a/libio/iofdopen.c
+++ b/libio/iofdopen.c
@@ -167,6 +167,15 @@ _IO_new_fdopen (fd, mode)
   _IO_mask_flags (&new_f->fp.file, read_write,
 		  _IO_NO_READS+_IO_NO_WRITES+_IO_IS_APPENDING);
 
+  /* For append mode, send the file offset to the end of the file.  Don't
+     update the offset cache though, since the file handle is not active.  */
+  if ((read_write & (_IO_IS_APPENDING | _IO_NO_READS))
+      == (_IO_IS_APPENDING | _IO_NO_READS))
+    {
+      _IO_off64_t new_pos = _IO_SYSSEEK (&new_f->fp.file, 0, _IO_seek_end);
+      if (new_pos == _IO_pos_BAD && errno != ESPIPE)
+	return NULL;
+    }
   return &new_f->fp.file;
 }
 libc_hidden_ver (_IO_new_fdopen, _IO_fdopen)
diff --git a/libio/tst-ftell-active-handler.c b/libio/tst-ftell-active-handler.c
index 5d5fc26..aef9cc0 100644
--- a/libio/tst-ftell-active-handler.c
+++ b/libio/tst-ftell-active-handler.c
@@ -88,6 +88,107 @@ static size_t file_len;
 typedef int (*fputs_func_t) (const void *data, FILE *fp);
 fputs_func_t fputs_func;
 
+/* Test that ftell output after a rewind is correct.  */
+static int
+do_rewind_test (const char *filename)
+{
+  int ret = 0;
+  struct test
+    {
+      const char *mode;
+      int fd_mode;
+      size_t old_off;
+      size_t new_off;
+    } test_modes[] = {
+	  {"w", O_WRONLY, 0, data_len},
+	  {"w+", O_RDWR, 0, data_len},
+	  {"r+", O_RDWR, 0, data_len},
+	  /* The new offsets for 'a' and 'a+' modes have to factor in the
+	     previous writes since they compulsorily append to the end of the
+	     file.  */
+	  {"a", O_WRONLY, 0, 3 * data_len},
+	  {"a+", O_RDWR, 0, 4 * data_len},
+    };
+
+  /* Empty the file before the test so that our offsets are simple to
+     calculate.  */
+  FILE *fp = fopen (filename, "w");
+  if (fp == NULL)
+    {
+      printf ("Failed to open file for emptying\n");
+      return 1;
+    }
+  fclose (fp);
+
+  for (int j = 0; j < 2; j++)
+    {
+      for (int i = 0; i < sizeof (test_modes) / sizeof (struct test); i++)
+	{
+	  FILE *fp;
+	  int fd;
+	  int fileret;
+
+	  printf ("\trewind: %s (file, \"%s\"): ", j == 0 ? "fdopen" : "fopen",
+		  test_modes[i].mode);
+
+	  if (j == 0)
+	    fileret = get_handles_fdopen (filename, fd, fp,
+					  test_modes[i].fd_mode,
+					  test_modes[i].mode);
+	  else
+	    fileret = get_handles_fopen (filename, fd, fp, test_modes[i].mode);
+
+	  if (fileret != 0)
+	    return fileret;
+
+	  /* Write some content to the file, rewind and ensure that the ftell
+	     output after the rewind is 0.  POSIX does not specify what the
+	     behavior is when a file is rewound in 'a' mode, so we retain
+	     current behavior, which is to keep the 0 offset.  */
+	  size_t written = fputs_func (data, fp);
+
+	  if (written == EOF)
+	    {
+	      printf ("fputs[1] failed to write data\n");
+	      ret |= 1;
+	    }
+
+	  rewind (fp);
+	  long offset = ftell (fp);
+
+	  if (offset != test_modes[i].old_off)
+	    {
+	      printf ("Incorrect old offset.  Expected %zu, but got %ld, ",
+		      test_modes[i].old_off, offset);
+	      ret |= 1;
+	    }
+	  else
+	    printf ("old offset = %ld, ", offset);
+
+	  written = fputs_func (data, fp);
+
+	  if (written == EOF)
+	    {
+	      printf ("fputs[1] failed to write data\n");
+	      ret |= 1;
+	    }
+
+	  /* After this write, the offset in append modes should factor in the
+	     implicit lseek to the end of file.  */
+	  offset = ftell (fp);
+	  if (offset != test_modes[i].new_off)
+	    {
+	      printf ("Incorrect new offset.  Expected %zu, but got %ld\n",
+		      test_modes[i].new_off, offset);
+	      ret |= 1;
+	    }
+	  else
+	    printf ("new offset = %ld\n", offset);
+	}
+    }
+  return ret;
+}
+
 /* Test that the value of ftell is not cached when the stream handle is not
    active.  */
 static int
@@ -107,11 +208,13 @@ do_ftell_test (const char *filename)
 	  {"w", O_WRONLY, 0, data_len},
 	  {"w+", O_RDWR, 0, data_len},
 	  {"r+", O_RDWR, 0, data_len},
-	  /* For 'a' and 'a+' modes, the initial file position should be the
+	  /* For the 'a' mode, the initial file position should be the
 	     current end of file. After the write, the offset has data_len
-	     added to the old value.  */
+	     added to the old value.  For a+ mode however, the initial file
+	     position is the file position of the underlying file descriptor,
+	     since it is initially assumed to be in read mode.  */
 	  {"a", O_WRONLY, data_len, 2 * data_len},
-	  {"a+", O_RDWR, 2 * data_len, 3 * data_len},
+	  {"a+", O_RDWR, 0, 3 * data_len},
     };
   for (int j = 0; j < 2; j++)
     {
@@ -157,7 +260,7 @@ do_ftell_test (const char *filename)
 	  if (off != test_modes[i].new_off)
 	    {
 	      printf ("Incorrect new offset.  Expected %zu but got %ld\n",
-		      test_modes[i].old_off, off);
+		      test_modes[i].new_off, off);
 	      ret |= 1;
 	    }
 	  else
@@ -322,6 +425,7 @@ do_one_test (const char *filename)
   ret |= do_ftell_test (filename);
   ret |= do_write_test (filename);
   ret |= do_append_test (filename);
+  ret |= do_rewind_test (filename);
 
   return ret;
 }
diff --git a/libio/wfileops.c b/libio/wfileops.c
index 8b2e108..3199861 100644
--- a/libio/wfileops.c
+++ b/libio/wfileops.c
@@ -597,12 +597,12 @@ done:
 }
 
 /* ftell{,o} implementation for wide mode.  Don't modify any state of the file
-   pointer while we try to get the current state of the stream.  */
+   pointer while we try to get the current state of the stream except in one
+   case, which is when we have unflushed writes in append mode.  */
 static _IO_off64_t
 do_ftell_wide (_IO_FILE *fp)
 {
   _IO_off64_t result, offset = 0;
-  bool use_cached_offset = false;
 
   /* No point looking for offsets in the buffer if it hasn't even been
      allocated.  */
@@ -615,6 +615,20 @@ do_ftell_wide (_IO_FILE *fp)
 			   > fp->_wide_data->_IO_write_base)
 			  || _IO_in_put_mode (fp));
 
+      bool append_mode = (fp->_flags & _IO_IS_APPENDING) == _IO_IS_APPENDING;
+
+      /* When we have unflushed writes in append mode, seek to the end of the
+	 file and record that offset.  This is the only time we change the file
+	 stream state and it is safe since the file handle is active.  */
+      if (was_writing && append_mode)
+	{
+	  result = _IO_SYSSEEK (fp, 0, _IO_seek_end);
+	  if (result == _IO_pos_BAD)
+	    return EOF;
+	  else
+	    fp->_offset = result;
+	}
+
       /* XXX For wide stream with backup store it is not very
 	 reasonable to determine the offset.  The pushed-back
 	 character might require a state change and we need not be
@@ -703,37 +717,24 @@ do_ftell_wide (_IO_FILE *fp)
 	     position is fp._offset - (_IO_read_end - new_write_ptr).  */
 	  offset -= fp->_IO_read_end - fp->_IO_write_ptr;
 	}
-
-      /* It is safe to use the cached offset when available if there is
-	 unbuffered data (indicating that the file handle is active) and
-	 the handle is not for a file open in a+ mode.  The latter
-	 condition is because there could be a scenario where there is a
-	 switch from read mode to write mode using an fseek to an arbitrary
-	 position.  In this case, there would be unbuffered data due to be
-	 appended to the end of the file, but the offset may not
-	 necessarily be the end of the file.  It is fine to use the cached
-	 offset when the a+ stream is in read mode though, since the offset
-	 is maintained correctly in that case.  Note that this is not a
-	 comprehensive set of cases when the offset is reliable.  The
-	 offset may be reliable even in some cases where there is no
-	 unflushed input and the handle is active, but it's just that we
-	 don't have a way to identify that condition reliably.  */
-      use_cached_offset = (offset != 0 && fp->_offset != _IO_pos_BAD
-			   && ((fp->_flags & (_IO_IS_APPENDING | _IO_NO_READS))
-			       == (_IO_IS_APPENDING | _IO_NO_READS)
-			       && was_writing));
     }
 
-  if (use_cached_offset)
+  if (fp->_offset != _IO_pos_BAD)
     result = fp->_offset;
   else
-    result = get_file_offset (fp);
+    result = _IO_SYSSEEK (fp, 0, _IO_seek_cur);
 
   if (result == EOF)
     return result;
 
   result += offset;
 
+  if (result < 0)
+    {
+      __set_errno (EINVAL);
+      return EOF;
+    }
+
   return result;
 }
 
