diff --git a/src/Data/LinearMap.hs b/src/Data/LinearMap.hs
--- a/src/Data/LinearMap.hs
+++ b/src/Data/LinearMap.hs
@@ -3,7 +3,7 @@
 ----------------------------------------------------------------------
 -- |
 -- Module      :  Data.LinearMap
--- Copyright   :  (c) Conal Elliott 2008
+-- Copyright   :  (c) Conal Elliott 2008-2012
 -- License     :  BSD3
 --
 -- Maintainer  :  conal@conal.net
@@ -24,11 +24,10 @@
 import Control.Applicative (Applicative,liftA2,liftA3)
 import Control.Arrow       (first)
 
-import Data.MemoTrie      ((:->:)(..))
+import Data.MemoTrie      (HasTrie(..),(:->:))
 import Data.AdditiveGroup (Sum(..), AdditiveGroup(..))
 import Data.VectorSpace   (VectorSpace(..))
 import Data.Basis         (HasBasis(..), linearCombo)
-
 
 -- Linear maps are almost but not quite a Control.Category.  The type
 -- class constraints interfere.  They're almost an Arrow also, but for the
diff --git a/vector-space.cabal b/vector-space.cabal
--- a/vector-space.cabal
+++ b/vector-space.cabal
@@ -1,5 +1,5 @@
 Name:                vector-space
-Version:             0.8.0
+Version:             0.8.1
 Cabal-Version:       >= 1.2
 Synopsis:            Vector & affine spaces, linear maps, and derivatives
 Category:            math
@@ -15,12 +15,12 @@
   .
   Project wiki page: <http://haskell.org/haskellwiki/vector-space>
   .
-  &#169; 2008-2011 by Conal Elliott; BSD3 license.
+  &#169; 2008-2012 by Conal Elliott; BSD3 license.
 Author:              Conal Elliott 
 Maintainer:          conal@conal.net
 Homepage:            http://haskell.org/haskellwiki/vector-space
 Package-Url:         http://code.haskell.org/vector-space
-Copyright:           (c) 2008-2011 by Conal Elliott
+Copyright:           (c) 2008-2012 by Conal Elliott
 License:             BSD3
 License-File:        COPYING
 Stability:           experimental
@@ -29,7 +29,7 @@
 Library
   hs-Source-Dirs:      src
   Extensions:          
-  Build-Depends:       base<5, MemoTrie >= 0.4.2, Boolean >= 0.0.1,
+  Build-Depends:       base<5, MemoTrie >= 0.5, Boolean >= 0.0.1,
                        NumInstances >= 1.0
   Exposed-Modules:     
                      Data.AdditiveGroup