diff --git a/Control/Monad/Logic.hs b/Control/Monad/Logic.hs
--- a/Control/Monad/Logic.hs
+++ b/Control/Monad/Logic.hs
@@ -22,13 +22,13 @@
 module Control.Monad.Logic (
     module Control.Monad.Logic.Class,
     -- * The Logic monad
-    Logic(),
+    Logic(..),
     runLogic,
     observe,
     observeMany,
     observeAll,
     -- * The LogicT monad transformer
-    LogicT(),
+    LogicT(..),
     runLogicT,
     observeT,
     observeManyT,
@@ -45,6 +45,7 @@
 
 import Control.Monad.Reader.Class
 import Control.Monad.State.Class
+import Control.Monad.Error.Class
 
 import qualified Data.Foldable as F
 import qualified Data.Traversable as T
@@ -193,3 +194,9 @@
     get = lift get
     put = lift . put
 
+-- Needs undecidable instances
+instance (MonadError e m) => MonadError e (LogicT m) where
+  throwError = lift . throwError
+  catchError m h = LogicT $ \sk fk -> let
+      handle r = r `catchError` \e -> unLogicT (h e) sk fk
+    in handle $ unLogicT m (\a -> sk a . handle) fk
diff --git a/LICENSE b/LICENSE
--- a/LICENSE
+++ b/LICENSE
@@ -1,6 +1,6 @@
 This module is under this "3 clause" BSD license:
 
-Copyright (c) 2007, Dan Doel
+Copyright (c) 2007-2010, Dan Doel
 All rights reserved.
 
 Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:
diff --git a/logict.cabal b/logict.cabal
--- a/logict.cabal
+++ b/logict.cabal
@@ -1,5 +1,5 @@
 Name:                   logict
-Version:                0.3
+Version:                0.4
 Description:            A continuation-based, backtracking, logic programming monad.
                         An adaptation of the two-continuation implementation found
                         in the paper "Backtracking, Interleaving, and Terminating
@@ -9,14 +9,14 @@
 Category:               Control
 License:                BSD3
 License-File:           LICENSE
-Copyright:              Copyright (c) 2007, Dan Doel
+Copyright:              Copyright (c) 2007-2010, Dan Doel
 Author:                 Dan Doel
 Maintainer:             dan.doel@gmail.com
 Homepage:               http://code.haskell.org/~dolio/logict
 
 Stability:              Experimental
 Tested-With:            GHC
-Build-Depends:          base, mtl>=1.0.1
+Build-Depends:          base >=2 && < 5, mtl>=1.0.1 && <1.2
 Build-Type:             Simple
 
 Exposed-Modules:        Control.Monad.Logic,