diff --git a/air-extra.cabal b/air-extra.cabal
--- a/air-extra.cabal
+++ b/air-extra.cabal
@@ -1,5 +1,5 @@
 Name:                 air-extra
-Version:              2011.10.12
+Version:              2012.5.15
 Build-type:           Simple
 Synopsis:             air-extra
 Description:          An alternative Haskell Prelude library, extra helpers
diff --git a/src/Air/Extra.hs b/src/Air/Extra.hs
--- a/src/Air/Extra.hs
+++ b/src/Air/Extra.hs
@@ -87,7 +87,7 @@
     collapse' [] _ r     = r
     collapse' (x:xs') q r = collapse' xs' (q+1) (r + x * 10 Prelude.^ q)
 
-base :: (Integral a) => a -> a -> String
+base :: (Integral a, Show a) => a -> a -> String
 base p n = showIntAtBase p intToDigit n ""
     
 -- String