diff -ur wvstreams-3.75.0/include/wvstring.h wvstreams-3.75.0.new/include/wvstring.h
--- wvstreams-3.75.0/include/wvstring.h	2004-03-13 19:59:36.000000000 +0100
+++ wvstreams-3.75.0.new/include/wvstring.h	2004-07-28 15:32:50.236903510 +0200
@@ -18,6 +18,7 @@
 #include <string.h>
 #include <stdio.h>
 #include <stdlib.h>
+#include <stddef.h>
 
 
 /*
@@ -66,7 +67,7 @@
 
 // the _actual_ space taken by a WvStringBuf, without the data[] array
 // (which is variable-sized, not really 1 byte)
-#define WVSTRINGBUF_SIZE(s) (s->data - (char *)s)
+#define WVSTRINGBUF_SIZE(s) (offsetof(struct WvStringBuf, data))
 
 /**
  * A WvFastString acts exactly like a WvString, but can take (const char *)