=== modified file 'src/xdisp.c'
--- src/xdisp.c	2012-12-11 12:22:35 +0000
+++ src/xdisp.c	2012-12-12 08:44:59 +0000
@@ -2589,7 +2589,7 @@
 	       ptrdiff_t charpos, ptrdiff_t bytepos,
 	       struct glyph_row *row, enum face_id base_face_id)
 {
-  int highlight_region_p;
+  ptrdiff_t markpos;
   enum face_id remapped_base_face_id = base_face_id;
 
   /* Some precondition checks.  */
@@ -2692,16 +2692,20 @@
   /* Are multibyte characters enabled in current_buffer?  */
   it->multibyte_p = !NILP (BVAR (current_buffer, enable_multibyte_characters));
 
-  /* Non-zero if we should highlight the region.  */
-  highlight_region_p
-    = (!NILP (Vtransient_mark_mode)
-       && !NILP (BVAR (current_buffer, mark_active))
-       && XMARKER (BVAR (current_buffer, mark))->buffer != 0);
+  /* If we should highlight the region and the region is
+     of non-zero length, store mark position in MARKPOS.  */
+  if (!NILP (Vtransient_mark_mode)
+      && !NILP (BVAR (current_buffer, mark_active))
+      && XMARKER (BVAR (current_buffer, mark))->buffer != NULL
+      && (markpos = XMARKER (BVAR (current_buffer, mark))->charpos) != PT)
+    /* nothing */;
+  else
+    markpos = -1;
 
   /* Set IT->region_beg_charpos and IT->region_end_charpos to the
      start and end of a visible region in window IT->w.  Set both to
      -1 to indicate no region.  */
-  if (highlight_region_p
+  if (markpos != -1
       /* Maybe highlight only in selected window.  */
       && (/* Either show region everywhere.  */
 	  highlight_nonselected_windows
@@ -2713,7 +2717,6 @@
 	      && WINDOWP (minibuf_selected_window)
 	      && w == XWINDOW (minibuf_selected_window))))
     {
-      ptrdiff_t markpos = marker_position (BVAR (current_buffer, mark));
       it->region_beg_charpos = min (PT, markpos);
       it->region_end_charpos = max (PT, markpos);
     }