doc updates based on review
diff --git a/docs/hazmat/backends/interfaces.rst b/docs/hazmat/backends/interfaces.rst
index e22c6bb..ca3a543 100644
--- a/docs/hazmat/backends/interfaces.rst
+++ b/docs/hazmat/backends/interfaces.rst
@@ -133,7 +133,6 @@
             :class:`~cryptography.hazmat.primitives.interfaces.HashContext`
 
 
-
 .. class:: PBKDF2HMACBackend
 
     .. versionadded:: 0.2
@@ -144,7 +143,7 @@
 
         Check if the specified ``algorithm`` is supported by this backend.
 
-        :param prf: An instance of a
+        :param algorithm: An instance of a
             :class:`~cryptography.hazmat.primitives.interfaces.HashAlgorithm`
             provider.