diff --git a/src/Data/Basis.hs b/src/Data/Basis.hs
--- a/src/Data/Basis.hs
+++ b/src/Data/Basis.hs
@@ -23,7 +23,7 @@
 
 -- import Control.Applicative ((<$>))
 import Control.Arrow (first)
-import Data.Either
+-- import Data.Either
 
 import Data.VectorSpace
 
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:             0.6.0
+Version:             0.6.1
 Cabal-Version:       >= 1.2
 Synopsis:            Vector & affine spaces, linear maps, and derivatives (requires ghc 6.9 or better)
 Category:            math
@@ -28,7 +28,7 @@
 Library
   hs-Source-Dirs:      src
   Extensions:          
-  Build-Depends:       base, MemoTrie >= 0.4.2, Boolean
+  Build-Depends:       base<5, MemoTrie >= 0.4.2, Boolean
   Exposed-Modules:     
                      Data.AdditiveGroup
                      Data.VectorSpace