diff --git a/Control/Monad/State/Class.hs b/Control/Monad/State/Class.hs
index f64fbf5f3b30b58d63f962e9309a285d8f162ad1..7dc0669ada5de1577b1fd54b26fa0dfcb642a447 100644
--- a/Control/Monad/State/Class.hs
+++ b/Control/Monad/State/Class.hs
@@ -202,6 +202,7 @@ instance
     put = lift . put
     state = lift . state
 
+-- | @since 2.3
 instance MonadState s m => MonadState s (SelectT r m) where
     get = lift get
     put = lift . put