diff --git a/requirements.txt b/requirements.txt
index 909810590..17458a189 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -7,7 +7,7 @@ mako
 chardet
 six
 setproctitle
-pywin32; sys.platform == 'win32'
-py2-ipaddress; sys.platform == 'win32'
-certifi; sys.platform == 'win32'
+pywin32; sys_platform == 'win32'
+py2-ipaddress; sys_platform == 'win32' and python_version == '2'
+certifi; sys_platform == 'win32'
 zope.interface>=4.4.2
diff --git a/setup.cfg b/setup.cfg
index 94cea1bd5..2cbd5785a 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -1,3 +1,6 @@
+[bdist_wheel]
+universal = 1
+
 [build_docs]
 source-dir = docs/source
 build-dir = docs/build
diff --git a/setup.py b/setup.py
index 7d1183da2..9ff305ef4 100755
--- a/setup.py
+++ b/setup.py
@@ -547,9 +547,9 @@ install_requires = [
     'chardet',
     'six',
     'setproctitle',
-    "pywin32; sys.platform == 'win32'",
-    "py2-ipaddress; sys.platform == 'win32'",
-    "certifi; sys.platform == 'win32'",
+    "pywin32; sys_platform == 'win32'",
+    "py2-ipaddress; sys_platform == 'win32' and python_version == '2'",
+    "certifi; sys_platform == 'win32'",
     'zope.interface',
 ]
 tests_require = ['pytest', 'pytest-twisted']