set defaults on build_ffi
diff --git a/cryptography/hazmat/bindings/commoncrypto/binding.py b/cryptography/hazmat/bindings/commoncrypto/binding.py
index ec98b33..144bb09 100644
--- a/cryptography/hazmat/bindings/commoncrypto/binding.py
+++ b/cryptography/hazmat/bindings/commoncrypto/binding.py
@@ -45,11 +45,6 @@
         cls.ffi, cls.lib = build_ffi(
             module_prefix=cls._module_prefix,
             modules=cls._modules,
-            pre_include="",
-            post_include="",
-            libraries=[],
-            extra_compile_args=[],
-            extra_link_args=[]
         )
 
     @classmethod
diff --git a/cryptography/hazmat/bindings/openssl/binding.py b/cryptography/hazmat/bindings/openssl/binding.py
index fab66c7..f0ff327 100644
--- a/cryptography/hazmat/bindings/openssl/binding.py
+++ b/cryptography/hazmat/bindings/openssl/binding.py
@@ -103,8 +103,6 @@
             pre_include=_OSX_PRE_INCLUDE,
             post_include=_OSX_POST_INCLUDE,
             libraries=libraries,
-            extra_compile_args=[],
-            extra_link_args=[]
         )
         res = cls.lib.Cryptography_add_osrandom_engine()
         assert res != 0
diff --git a/cryptography/hazmat/bindings/utils.py b/cryptography/hazmat/bindings/utils.py
index 9d6956f..1c48116 100644
--- a/cryptography/hazmat/bindings/utils.py
+++ b/cryptography/hazmat/bindings/utils.py
@@ -20,8 +20,8 @@
 import cffi
 
 
-def build_ffi(module_prefix, modules, pre_include, post_include, libraries,
-              extra_compile_args, extra_link_args):
+def build_ffi(module_prefix, modules, pre_include="", post_include="",
+              libraries=[], extra_compile_args=[], extra_link_args=[]):
     """
     Modules listed in ``modules`` should have the following attributes: