diff --git a/air.cabal b/air.cabal
--- a/air.cabal
+++ b/air.cabal
@@ -1,5 +1,5 @@
 Name:                 air
-Version:              2011.10.19
+Version:              2012.5.15
 Build-type:           Simple
 Synopsis:             air
 Description:          An alternative Haskell Prelude library.
diff --git a/src/Air/Light.hs b/src/Air/Light.hs
--- a/src/Air/Light.hs
+++ b/src/Air/Light.hs
@@ -286,7 +286,7 @@
 
 
 -- New from Lab
-at :: (Show a, Integral i) => i -> [a] -> a
+at :: (Show a, Integral i, Show i) => i -> [a] -> a
 at i xs = if i P.< xs.length
   then xs !! i
   else error - show xs ++ " at " ++ show i ++ " failed"