diff --git a/ChangeLog b/ChangeLog
index 143c490974..3a0c85eddb 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Mon Jan 25 17:47:02 2010  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* ext/pty/pty.c (pty_check): needs WNOHANG to poll, return $?, and
+	  call raise_from_check() with pid_t.  [ruby-dev:40141]
+
 Mon Jan 25 17:36:11 2010  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	* version.c (RUBY_LIB, RUBY_*_LIB): moved from configures.
diff --git a/ext/pty/pty.c b/ext/pty/pty.c
index b4394c207c..a94d2f249f 100644
--- a/ext/pty/pty.c
+++ b/ext/pty/pty.c
@@ -605,11 +605,11 @@ pty_check(int argc, VALUE *argv, VALUE self)
     int status;
 
     rb_scan_args(argc, argv, "11", &pid, &exc);
-    cpid = rb_waitpid(NUM2PIDT(pid), &status, WUNTRACED);
+    cpid = rb_waitpid(NUM2PIDT(pid), &status, WNOHANG|WUNTRACED);
     if (cpid == -1) return Qnil;
 
-    if (!RTEST(exc)) return status;
-    raise_from_check(pid, status);
+    if (!RTEST(exc)) return rb_last_status_get();
+    raise_from_check(cpid, status);
     return Qnil;		/* not reached */
 }