diff --git a/Data/MemoCombinators/Class.hs b/Data/MemoCombinators/Class.hs
--- a/Data/MemoCombinators/Class.hs
+++ b/Data/MemoCombinators/Class.hs
@@ -74,6 +74,8 @@
 
 instance (MemoTable a) => MemoTable [a] where table = Memo.list table
 instance (MemoTable a) => MemoTable (Maybe a) where table = Memo.maybe table
+instance (MemoTable a, MemoTable b) => MemoTable (Either a b) where 
+    table = Memo.either table table
 instance (Integral a, MemoTable a) => MemoTable (Ratio a) where
     table = Memo.wrap (uncurry (%)) (numerator &&& denominator) table
 
diff --git a/data-memocombinators.cabal b/data-memocombinators.cabal
--- a/data-memocombinators.cabal
+++ b/data-memocombinators.cabal
@@ -1,7 +1,7 @@
 Name: data-memocombinators
 Description:
     Combinators for building memo tables.
-Version: 0.5.0
+Version: 0.5.1
 Stability: experimental
 Synopsis: Combinators for building memo tables.
 License: BSD3