diff --git a/Yesod/Auth.hs b/Yesod/Auth.hs
--- a/Yesod/Auth.hs
+++ b/Yesod/Auth.hs
@@ -34,6 +34,8 @@
     , AuthException (..)
       -- * Helper
     , AuthHandler
+      -- * Internal
+    , credsKey
     ) where
 
 import Control.Monad                 (when)
@@ -163,6 +165,9 @@
         => HandlerT master IO (Maybe (AuthId master))
     maybeAuthId = defaultMaybeAuthId
 
+-- | Internal session key used to hold the authentication information.
+--
+-- Since 1.2.3
 credsKey :: Text
 credsKey = "_ID"
 
diff --git a/yesod-auth.cabal b/yesod-auth.cabal
--- a/yesod-auth.cabal
+++ b/yesod-auth.cabal
@@ -1,5 +1,5 @@
 name:            yesod-auth
-version:         1.2.3
+version:         1.2.4
 license:         MIT
 license-file:    LICENSE
 author:          Michael Snoyman, Patrick Brisbin