diff --git a/cryptography/hazmat/backends/interfaces.py b/cryptography/hazmat/backends/interfaces.py
index 9539d83..4137b53 100644
--- a/cryptography/hazmat/backends/interfaces.py
+++ b/cryptography/hazmat/backends/interfaces.py
@@ -153,7 +153,7 @@
         """
 
     @abc.abstractmethod
-    def create_cmac_ctx(self, key, algorithm):
+    def create_cmac_ctx(self, algorithm):
         """
         Create a CMACContext for calculating a message authentication code.
         """