diff --git a/ChangeLog b/ChangeLog
index 97bce8a940..74c5eeb3d6 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+Tue Sep  3 11:23:57 2013  NAKAMURA Usaku  <usa@ruby-lang.org>
+
+	* win32/win32.c (rb_w32_select_with_thread): rounding up the fraction of
+	  tv_usec instead of rounding down.
+	  this change is an experiment to get rid of failures on vc10-x64 CI.
+
 Tue Sep  3 11:00:28 2013  NAKAMURA Usaku  <usa@ruby-lang.org>
 
 	* win32/win32.c (do_select): constify timeout.
diff --git a/win32/win32.c b/win32/win32.c
index fa96d417d1..15c6020dc8 100644
--- a/win32/win32.c
+++ b/win32/win32.c
@@ -2960,7 +2960,7 @@ rb_w32_select_with_thread(int nfds, fd_set *rd, fd_set *wr, fd_set *ex,
 		    if (!rb_w32_time_subtract(&rest, &now)) break;
 		    if (compare(&rest, &wait) < 0) dowait = &rest;
 		}
-		Sleep(dowait->tv_sec * 1000 + dowait->tv_usec / 1000);
+		Sleep(dowait->tv_sec * 1000 + (dowait->tv_usec + 999) / 1000);
 	    }
 	}
     }