--- src/lib/libc/stdio/vsprintf.c	2005/07/23 23:14:44	1.7
+++ src/lib/libc/stdio/vsprintf.c	2006/03/02 18:05:30	1.8
@@ -59,6 +59,7 @@ vsprintf(char *str, const char *fmt, va_
 	f.fl_mutex = PTHREAD_MUTEX_INITIALIZER;
 	f.fl_owner = NULL;
 	f.fl_count = 0;
+	memset(WCIO_GET(&f), 0, sizeof(struct wchar_io_data));
 	ret = __vfprintf(&f, fmt, ap);
 	*f.pub._p = 0;
 	return (ret);