2 files changed, 6 insertions, 0 deletions
diff --git a/ChangeLog b/ChangeLog
index cd1361e25a..2b56c0bae0 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Fri Jul  8 21:49:28 2016  Naohisa Goto  <ngotogenome@gmail.com>
+
+	* thread.c (rb_wait_for_single_fd): Clean up fds.revents every time
+	  before calling ppoll(2). [Bug #12575] [ruby-dev:49725]
+
 Fri Jul  8 14:16:48 2016  Shugo Maeda  <shugo@ruby-lang.org>
 
 	* vm_args.c (vm_caller_setup_arg_block): call rb_sym_to_proc()
diff --git a/thread.c b/thread.c
index 1aa1c7983e..a53117ab82 100644
--- a/thread.c
+++ b/thread.c
@@ -3851,6 +3851,7 @@ rb_wait_for_single_fd(int fd, int events, struct timeval *tv)
     fds.events = (short)events;
 
     do {
+	fds.revents = 0;
 	lerrno = 0;
 	BLOCKING_REGION({
 	    result = ppoll(&fds, 1, timeout, NULL);