diff --git a/Lib/urllib.py b/Lib/urllib.py
index f84ac28..bf5fc97 100644
--- a/Lib/urllib.py
+++ b/Lib/urllib.py
@@ -1321,6 +1321,24 @@
 
 
 if sys.platform == 'darwin':
+
+    def _CFSetup(sc):
+        from ctypes import c_int32, c_void_p, c_char_p, c_int
+        sc.CFStringCreateWithCString.argtypes = [ c_void_p, c_char_p, c_int32 ]
+        sc.CFStringCreateWithCString.restype = c_void_p
+        sc.SCDynamicStoreCopyProxies.argtypes = [ c_void_p ]
+        sc.SCDynamicStoreCopyProxies.restype = c_void_p
+        sc.CFDictionaryGetValue.argtypes = [ c_void_p, c_void_p ]
+        sc.CFDictionaryGetValue.restype = c_void_p
+        sc.CFStringGetLength.argtypes = [ c_void_p ]
+        sc.CFStringGetLength.restype = c_int32
+        sc.CFStringGetCString.argtypes = [ c_void_p, c_char_p, c_int32, c_int32 ]
+        sc.CFStringGetCString.restype = c_int32
+        sc.CFNumberGetValue.argtypes = [ c_void_p, c_int, c_void_p ]
+        sc.CFNumberGetValue.restype = c_int32
+        sc.CFRelease.argtypes = [ c_void_p ]
+        sc.CFRelease.restype = None
+
     def _CStringFromCFString(sc, value):
         from ctypes import create_string_buffer
         length = sc.CFStringGetLength(value) + 1
@@ -1357,6 +1375,7 @@
             return (parts[0] << 24) | (parts[1] << 16) | (parts[2] << 8) | parts[3]
 
         sc = cdll.LoadLibrary(find_library("SystemConfiguration"))
+        _CFSetup(sc)
 
         hostIP = None
 
@@ -1369,6 +1388,8 @@
 
 
         proxyDict = sc.SCDynamicStoreCopyProxies(None)
+        if proxyDict is None:
+            return False
 
         try:
             # Check for simple host names:
@@ -1422,11 +1443,11 @@
         from ctypes.util import find_library
 
         sc = cdll.LoadLibrary(find_library("SystemConfiguration"))
+        _CFSetup(sc)
 
         if not sc:
             return {}
 
-
         kSCPropNetProxiesHTTPEnable = sc.CFStringCreateWithCString(0, "HTTPEnable", 0)
         kSCPropNetProxiesHTTPProxy = sc.CFStringCreateWithCString(0, "HTTPProxy", 0)
         kSCPropNetProxiesHTTPPort = sc.CFStringCreateWithCString(0, "HTTPPort", 0)