Merge pull request #227 from dreid/explicit-backend-in-hazmat

Explicit backend

1 files changed, 1 insertions, 5 deletions

diff --git a/cryptography/hazmat/primitives/hmac.py b/cryptography/hazmat/primitives/hmac.py
index 08dfae01..618bccc5 100644
--- a/cryptography/hazmat/primitives/hmac.py
+++ b/cryptography/hazmat/primitives/hmac.py
@@ -22,15 +22,11 @@ from cryptography.hazmat.primitives import interfaces
 
 @utils.register_interface(interfaces.HashContext)
 class HMAC(object):
-    def __init__(self, key, algorithm, ctx=None, backend=None):
+    def __init__(self, key, algorithm, backend, ctx=None):
         if not isinstance(algorithm, interfaces.HashAlgorithm):
             raise TypeError("Expected instance of interfaces.HashAlgorithm.")
         self.algorithm = algorithm
 
-        if backend is None:
-            from cryptography.hazmat.bindings import _default_backend
-            backend = _default_backend
-
         self._backend = backend
         self._key = key
         if ctx is None: