Fixed python3 incompatibility
diff --git a/cryptography/hazmat/bindings/commoncrypto/binding.py b/cryptography/hazmat/bindings/commoncrypto/binding.py
index f10e9bd..ee80942 100644
--- a/cryptography/hazmat/bindings/commoncrypto/binding.py
+++ b/cryptography/hazmat/bindings/commoncrypto/binding.py
@@ -47,5 +47,5 @@
 
     @classmethod
     def is_available(cls):
-        return sys.platform == "darwin" and map(
-            int, platform.mac_ver()[0].split(".")) >= [10, 8, 0]
+        return sys.platform == "darwin" and list(map(
+            int, platform.mac_ver()[0].split("."))) >= [10, 8, 0]