diff --git a/docs/primitives/cryptographic-hashes.rst b/docs/primitives/cryptographic-hashes.rst
index d4dde04..aeb30f4 100644
--- a/docs/primitives/cryptographic-hashes.rst
+++ b/docs/primitives/cryptographic-hashes.rst
@@ -1,11 +1,13 @@
 Message Digests
 ===============
 
-.. class:: cryptography.primitives.hashes.BaseHash
+.. class:: cryptography.primitives.hashes.BaseHash(data=None)
 
    Abstract base class that implements a common interface for all hash
    algorithms that follow here.
 
+   If ``data`` is provided ``update(data)`` is called upon construction.
+
     .. method:: update(data)
 
         :param bytes data: The bytes you wish to hash.