diff --git a/Lib/subprocess.py b/Lib/subprocess.py
index c02fb52..98a25b3 100644
--- a/Lib/subprocess.py
+++ b/Lib/subprocess.py
@@ -1112,8 +1112,14 @@ class Popen(object):
                 if fd >= start_fd:
                     os.closerange(start_fd, fd)
                     start_fd = fd + 1
-            if start_fd <= MAXFD:
-                os.closerange(start_fd, MAXFD)
+            maxfd = MAXFD
+            try:
+                maxfd = os.dup(0) + 1
+            except:
+                pass
+
+            if start_fd <= maxfd:
+                os.closerange(start_fd, maxfd)
 
 
         def _execute_child(self, args, executable, preexec_fn, close_fds,