diff --git a/README.rst b/README.rst
index 0b73f59..64e9119 100644
--- a/README.rst
+++ b/README.rst
@@ -87,7 +87,7 @@ constructor as bytes in the PEM format, or configure the key resolver as follows
 
 Digest algorithms
 ~~~~~~~~~~~~~~~~~
-The library supports SHA-512 digests via subclassing::
+If you need to generate a Content-Digest header using SHA-512, you can do so via subclassing::
 
   class MySigner(HTTPSignatureAuth):
       def add_digest(self, request):