diff --git a/winsup/cygwin/fhandler.h b/winsup/cygwin/fhandler.h
index f0c612d8a..497612ae1 100644
--- a/winsup/cygwin/fhandler.h
+++ b/winsup/cygwin/fhandler.h
@@ -2650,6 +2650,7 @@ class fhandler_signalfd : public fhandler_base
   int signalfd (const sigset_t *mask, int flags);
   int __reg2 fstat (struct stat *buf);
   void __reg3 read (void *ptr, size_t& len);
+  ssize_t __stdcall write (const void *, size_t);
 
   int poll ();
   inline sigset_t get_sigset () const { return sigset; }
@@ -2693,6 +2694,7 @@ class fhandler_timerfd : public fhandler_base
 
   int __reg2 fstat (struct stat *buf);
   void __reg3 read (void *ptr, size_t& len);
+  ssize_t __stdcall write (const void *, size_t);
   int dup (fhandler_base *child, int);
   int ioctl (unsigned int, void *);
   int close ();
diff --git a/winsup/cygwin/fhandler_signalfd.cc b/winsup/cygwin/fhandler_signalfd.cc
index d8e17a8fc..6c7da02e9 100644
--- a/winsup/cygwin/fhandler_signalfd.cc
+++ b/winsup/cygwin/fhandler_signalfd.cc
@@ -49,6 +49,7 @@ fhandler_signalfd::signalfd (const sigset_t *mask, int flags)
       nohandle (true);
       set_unique_id ();
       set_ino (get_unique_id ());
+      set_flags (O_RDWR | O_BINARY);
     }
   return 0;
 }
@@ -139,6 +140,13 @@ fhandler_signalfd::read (void *ptr, size_t& len)
   return;
 }
 
+ssize_t __stdcall
+fhandler_signalfd::write (const void *, size_t)
+{
+  set_errno (EINVAL);
+  return -1;
+}
+
 /* Called from select */
 int
 fhandler_signalfd::poll ()
diff --git a/winsup/cygwin/fhandler_timerfd.cc b/winsup/cygwin/fhandler_timerfd.cc
index 360731ca1..c7ff9c162 100644
--- a/winsup/cygwin/fhandler_timerfd.cc
+++ b/winsup/cygwin/fhandler_timerfd.cc
@@ -44,12 +44,10 @@ fhandler_timerfd::timerfd (clockid_t clock_id, int flags)
     set_nonblocking (true);
   if (flags & TFD_CLOEXEC)
     set_close_on_exec (true);
-  if (get_unique_id () == 0)
-    {
-      nohandle (true);
-      set_unique_id ();
-      set_ino (get_unique_id ());
-    }
+  nohandle (true);
+  set_unique_id ();
+  set_ino (get_unique_id ());
+  set_flags (O_RDWR | O_BINARY);
   return 0;
 }
 
@@ -125,6 +123,13 @@ fhandler_timerfd::read (void *ptr, size_t& len)
   return;
 }
 
+ssize_t __stdcall
+fhandler_timerfd::write (const void *, size_t)
+{
+  set_errno (EINVAL);
+  return -1;
+}
+
 HANDLE
 fhandler_timerfd::get_timerfd_handle ()
 {