diff -r 07c593845994 Lib/multiprocessing/popen_fork.py
--- a/Lib/multiprocessing/popen_fork.py	Sat Oct 01 22:05:07 2016 -0400
+++ b/Lib/multiprocessing/popen_fork.py	Sun Oct 02 04:34:07 2016 +0000
@@ -14,8 +14,10 @@
     method = 'fork'
 
     def __init__(self, process_obj):
-        sys.stdout.flush()
-        sys.stderr.flush()
+        if not sys.stdout.closed:
+            sys.stdout.flush()
+        if not sys.stderr.closed:
+            sys.stderr.flush()
         self.returncode = None
         self._launch(process_obj)
 
diff -r 07c593845994 Lib/test/test_multiprocessing_main_handling.py
--- a/Lib/test/test_multiprocessing_main_handling.py	Sat Oct 01 22:05:07 2016 -0400
+++ b/Lib/test/test_multiprocessing_main_handling.py	Sun Oct 02 04:34:07 2016 +0000
@@ -38,7 +38,7 @@
 
 import sys
 import time
-from multiprocessing import Pool, set_start_method
+from multiprocessing import Pool, Process, set_start_method
 
 # We use this __main__ defined function in the map call below in order to
 # check that multiprocessing in correctly running the unguarded
@@ -65,6 +65,13 @@
             raise RuntimeError("Timed out waiting for results")
     results.sort()
     print(start_method, "->", results)
+    sys.stdout.close()
+    sys.stderr.close()
+    process = Process(target=f, args=(1,))
+    process.start()
+    process.join(10)
+    if process.is_alive():
+        raise RuntimeError("Timed out waiting for single process")
 """
 
 test_source_main_skipped_in_children = """\