diff --git a/ChangeLog b/ChangeLog
index 888fcb990..6fd653cc2 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,10 @@
+2003-09-29  Havoc Pennington  <hp@redhat.com>
+
+	* src/xprops.c (cvtINT16toInt): fix the 64-bit check not to use 
+	macros from the X tree that don't get set
+
+	* configure.in: check for sizes of various types
+
 2003-09-29  Havoc Pennington  <hp@redhat.com>
 
 	* src/delete.c (meta_window_delete): don't move the focus after
diff --git a/configure.in b/configure.in
index cd50cc1ad..fbe7ad1d5 100644
--- a/configure.in
+++ b/configure.in
@@ -23,6 +23,18 @@ AC_HEADER_STDC
 AC_LIBTOOL_WIN32_DLL
 AM_PROG_LIBTOOL
 
+#### Integer sizes 
+
+AC_CHECK_SIZEOF(char)
+AC_CHECK_SIZEOF(short)
+AC_CHECK_SIZEOF(long)
+AC_CHECK_SIZEOF(int)
+AC_CHECK_SIZEOF(void *)
+AC_CHECK_SIZEOF(long long)
+AC_CHECK_SIZEOF(__int64)
+
+#### Warnings
+
 changequote(,)dnl
 if test "x$GCC" = "xyes"; then
   case " $CFLAGS " in
diff --git a/src/xprops.c b/src/xprops.c
index d8859ab03..cc9bd97c2 100644
--- a/src/xprops.c
+++ b/src/xprops.c
@@ -657,7 +657,7 @@ meta_prop_get_text_property (MetaDisplay   *display,
 
 /* From Xmd.h */
 #ifndef cvtINT32toInt
-#if defined(WORD64) && defined(UNSIGNEDBITFIELDS)
+#if SIZEOF_VOID_P == 8
 #define cvtINT8toInt(val)   (((val) & 0x00000080) ? ((val) | 0xffffffffffffff00) : (val))
 #define cvtINT16toInt(val)  (((val) & 0x00008000) ? ((val) | 0xffffffffffff0000) : (val))
 #define cvtINT32toInt(val)  (((val) & 0x80000000) ? ((val) | 0xffffffff00000000) : (val))
@@ -677,7 +677,7 @@ meta_prop_get_text_property (MetaDisplay   *display,
 #define cvtINT8toLong(val) (val)
 #define cvtINT16toLong(val) (val)
 #define cvtINT32toLong(val) (val)
-#endif /* WORD64 and UNSIGNEDBITFIELDS */
+#endif /* SIZEOF_VOID_P == 8 */
 #endif /* cvtINT32toInt() */
 
 static gboolean