PBKDF2HMAC requires a PBKDF2HMACBackend provider.

I cannot be trusted with a pasteboard
diff --git a/docs/hazmat/primitives/key-derivation-functions.rst b/docs/hazmat/primitives/key-derivation-functions.rst
index 529f441..551dbd6 100644
--- a/docs/hazmat/primitives/key-derivation-functions.rst
+++ b/docs/hazmat/primitives/key-derivation-functions.rst
@@ -80,7 +80,7 @@
         keys. See OWASP's `Password Storage Cheat Sheet`_ for more
         detailed recommendations if you intend to use this for password storage.
     :param backend: A
-        :class:`~cryptography.hazmat.backends.interfaces.CipherBackend`
+        :class:`~cryptography.hazmat.backends.interfaces.PBKDF2HMACBackend`
         provider.
 
     .. method:: derive(key_material)