diff --git a/MemoTrie.cabal b/MemoTrie.cabal
--- a/MemoTrie.cabal
+++ b/MemoTrie.cabal
@@ -1,5 +1,5 @@
 Name:                MemoTrie
-Version:             0.6.1
+Version:             0.6.2
 Cabal-Version:       >= 1.6
 Synopsis:            Trie-based memo functions
 Category:            Data
@@ -31,3 +31,4 @@
   Exposed-Modules:     
                      Data.MemoTrie
 
+ ghc-prof-options:    -prof -auto-all 
diff --git a/src/Data/MemoTrie.hs b/src/Data/MemoTrie.hs
--- a/src/Data/MemoTrie.hs
+++ b/src/Data/MemoTrie.hs
@@ -98,9 +98,7 @@
 -}
 
 
-{-# RULES
-"trie/untrie"   forall t. trie (untrie t) = t
- #-}
+{-# RULES "trie/untrie"   forall t. trie (untrie t) = t #-}
 
 -- Don't include the dual rule:
 --   "untrie/trie"   forall f. untrie (trie f) = f