diff --git a/winsup/cygwin/ChangeLog b/winsup/cygwin/ChangeLog
index d82cb12a4..9c5f590e4 100644
--- a/winsup/cygwin/ChangeLog
+++ b/winsup/cygwin/ChangeLog
@@ -1,3 +1,7 @@
+Mon Jul  4 19:29:00 2000  Corinna Vinschen  <corinna@vinschen.de>
+
+	* poll.cc (poll): Zero out `open_fds' as well.
+
 Mon Jul  4 19:22:00 2000  Corinna Vinschen  <corinna@vinschen.de>
 
 	* include/cygwin/version.h: Bump API minor version to 24.
diff --git a/winsup/cygwin/poll.cc b/winsup/cygwin/poll.cc
index e806b5ed0..dba674bdd 100644
--- a/winsup/cygwin/poll.cc
+++ b/winsup/cygwin/poll.cc
@@ -19,6 +19,7 @@ poll (struct pollfd *fds, unsigned int nfds, int timeout)
   fd_set open_fds, read_fds, write_fds, except_fds;
   struct timeval tv = { timeout / 1000, (timeout % 1000) * 1000 };
 
+  FD_ZERO (&open_fds);
   FD_ZERO (&read_fds);
   FD_ZERO (&write_fds);
   FD_ZERO (&except_fds);