diff --git a/Lib/subprocess.py b/Lib/subprocess.py
index 6a86397..06454f3 100644
--- a/Lib/subprocess.py
+++ b/Lib/subprocess.py
@@ -376,6 +376,12 @@
     import fcntl
     import pickle
 
+    # When select or poll has indicated that the file is writable,
+    # we can write up to _PIPE_BUF bytes without risk of blocking.
+    # POSIX defines PIPE_BUF as >= 512.
+    _PIPE_BUF = getattr(select, 'PIPE_BUF', 512)
+
+
 __all__ = ["Popen", "PIPE", "STDOUT", "call", "check_call", "getstatusoutput",
            "getoutput", "check_output", "CalledProcessError"]
 
@@ -384,11 +390,6 @@
 except:
     MAXFD = 256
 
-# When select or poll has indicated that the file is writable,
-# we can write up to _PIPE_BUF bytes without risk of blocking.
-# POSIX defines PIPE_BUF as >= 512.
-_PIPE_BUF = getattr(select, 'PIPE_BUF', 512)
-
 _active = []
 
 def _cleanup():
diff --git a/Lib/test/test_subprocess.py b/Lib/test/test_subprocess.py
index f2a396c..265859a 100644
--- a/Lib/test/test_subprocess.py
+++ b/Lib/test/test_subprocess.py
@@ -801,7 +801,7 @@
 
 unit_tests = [ProcessTestCase, CommandTests]
 
-if subprocess._has_poll:
+if getattr(subprocess, '_has_poll', False):
     class ProcessTestCaseNoPoll(ProcessTestCase):
         def setUp(self):
             subprocess._has_poll = False