diff -up emacs-23.1.90/src/xterm.c\~ emacs-23.1.90/src/xterm.c
--- emacs-23.1.90/src/xterm.c~	2009-12-10 08:52:48.000000000 +0900
+++ emacs-23.1.90/src/xterm.c	2009-12-10 08:57:22.000000000 +0900
@@ -10340,6 +10340,8 @@ x_term_init (display_name, xrm_option, r
       mm = DisplayWidthMM (dpyinfo->display, screen_number);
       /* Mac OS X 10.3's Xserver sometimes reports 0.0mm.  */
       dpyinfo->resx = (mm < 1) ? 100 : pixels * 25.4 / mm;
+      dpyinfo->resy = 96;
+      dpyinfo->resx = 96;
     }
 
   dpyinfo->Xatom_wm_protocols
