diff --git a/AUTHORS b/AUTHORS
index 24efac7..da0538a 100644
--- a/AUTHORS
+++ b/AUTHORS
@@ -49,4 +49,5 @@ Thanks To
 * Benoit Chesneau, bug report on green.os and patch to fix it
 * Slant, better iterator implementation in tpool
 * Ambroff, nice pygtk hub example
-* Michael Carter, and Marcin Bachry, nice repro of a bug and good diagnosis leading to the fix
\ No newline at end of file
+* Michael Carter, and Marcin Bachry, nice repro of a bug and good diagnosis leading to the fix
+* David Ziegler, reporting issue #53
\ No newline at end of file
diff --git a/eventlet/green/os.py b/eventlet/green/os.py
index 0fbfde5..1db46bc 100644
--- a/eventlet/green/os.py
+++ b/eventlet/green/os.py
@@ -72,7 +72,7 @@ def waitpid(pid, options):
     if options & os_orig.WNOHANG != 0:
         return __original_waitpid__(pid, options)
     else:
-        new_options = options | os.WNOHANG
+        new_options = options | os_orig.WNOHANG
         while True:
             rpid, status = __original_waitpid__(pid, new_options)
             if status >= 0: