diff --git a/setup.py b/setup.py
index e5ad7b9..007981e 100755
--- a/setup.py
+++ b/setup.py
@@ -29,6 +29,7 @@ import time
 import errno
 import platform
 from traceback import print_exc
+from sysconfig import _POSIX_BUILD
 
 try:
     import cffi
@@ -170,7 +171,7 @@ def bundled_settings(debug):
     # is this necessary?
     if sys.platform.startswith('freebsd'):
         settings['libraries'].append('pthread')
-    elif sys.platform.startswith('win'):
+    elif sys.platform.startswith('win') and not _POSIX_BUILD:
         # link against libzmq in build dir:
         plat = distutils.util.get_platform()
         temp = 'temp.%s-%i.%i' % (plat, sys.version_info[0], sys.version_info[1])
@@ -534,7 +535,7 @@ class Configure(build_ext):
             )
             line()
 
-        if sys.platform.startswith('win'):
+        if sys.platform.startswith('win') and not _POSIX_BUILD:
             # fetch libzmq.dll into local dir
             local_dll = localpath('zmq', libzmq_name + '.dll')
             if not zmq_prefix and not os.path.exists(local_dll):
@@ -626,7 +627,7 @@ class Configure(build_ext):
             libzmq.define_macros.append(('ZMQ_IOTHREADS_USE_POLL', 1))
             libzmq.define_macros.append(('ZMQ_POLL_BASED_ON_POLL', 1))
 
-        if sys.platform.startswith('win'):
+        if sys.platform.startswith('win') and not _POSIX_BUILD:
             # include defines from zeromq msvc project:
             libzmq.define_macros.append(('FD_SETSIZE', 16384))
             libzmq.define_macros.append(('DLL_EXPORT', 1))