diff --git a/ChangeLog b/ChangeLog
index 4021f4c267..19b685f1af 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+Tue Sep 23 19:38:03 2008  NAKAMURA Usaku  <usa@ruby-lang.org>
+
+	* win32/win32.c (subtruct): check tv_sec. reported by ko1.
+
 Tue Sep 23 19:21:03 2008  Tadayoshi Funaba  <tadf@dotrb.org>
 
 	* complex.c (nucomp_s_canonicalize_internal): does no apply
diff --git a/win32/win32.c b/win32/win32.c
index 5774d0c503..bcf4bd77ea 100644
--- a/win32/win32.c
+++ b/win32/win32.c
@@ -2157,6 +2157,9 @@ do_select(int nfds, fd_set *rd, fd_set *wr, fd_set *ex,
 static inline int
 subtract(struct timeval *rest, const struct timeval *wait)
 {
+    if (rest->tv_sec < wait->tv_sec) {
+	return 0;
+    }
     while (rest->tv_usec < wait->tv_usec) {
 	if (rest->tv_sec <= wait->tv_sec) {
 	    return 0;