Index: ../src/doprnt.c
===================================================================
--- ../src/doprnt.c	(revision 725)
+++ ../src/doprnt.c	(working copy)
@@ -95,10 +95,18 @@
   if (format_end == 0)
     format_end = format + strlen (format);
 
-  if ((format_end - format + 1) < sizeof (fixed_buffer))
+
+#if defined(_MSC_VER) && defined(_M_X64) 
+  if ((format_end - format + 1 + 3) < sizeof (fixed_buffer))
     fmtcpy = fixed_buffer;
   else
-    fmtcpy = (char *) alloca (format_end - format + 1);
+    fmtcpy = (char *) alloca (format_end - format + 1 + 3);
+#else
+  if ((format_end - format + 1 + 1) < sizeof (fixed_buffer))
+    fmtcpy = fixed_buffer;
+  else
+    fmtcpy = (char *) alloca (format_end - format + 1 + 1);
+#endif
 
   bufsize--;
 
@@ -173,12 +181,23 @@
 		error ("Not enough arguments for format string");
 	      if (sizeof (int) == sizeof (EMACS_INT))
 		;
+#if !defined(_MSC_VER) || !defined(_M_X64) && !defined(_M_IA64)
 	      else if (sizeof (long) == sizeof (EMACS_INT))
 		/* Insert an `l' the right place.  */
 		string[1] = string[0],
 		string[0] = string[-1],
 		string[-1] = 'l',
 		string++;
+#else
+	      else if (sizeof (__int64) == sizeof (EMACS_INT)) {
+		  string[3] = string[0];
+		  string[2] = string[-1];
+		  string[1] = '4';
+		  string[0] = '6';
+		  string[-1] = 'I';
+		  string += 3;
+	        } 
+#endif
 	      else
 		abort ();
 	      sprintf (sprintf_buffer, fmtcpy, args[cnt++]);