diff --git a/iban.cabal b/iban.cabal
--- a/iban.cabal
+++ b/iban.cabal
@@ -2,7 +2,7 @@
 -- see http://haskell.org/cabal/users-guide/
 
 name:                iban
-version:             0.1.1.0
+version:             0.1.1.1
 synopsis:            Validate and generate IBANs
 description:         A library to validate and generate (for now only German) IBANs.
 homepage:            https://github.com/ibotty/iban
@@ -25,7 +25,7 @@
                      , Finance.IBAN.Data
   -- other-modules:       
   other-extensions:    OverloadedStrings
-  build-depends:       base >=4.5 && <4.8
+  build-depends:       base >=4.5 && <4.10
                      , containers >=0.3 && <0.6
                      , iso3166-country-codes
                      , text >=0.11 && <1.3
diff --git a/src/Finance/IBAN/Internal.hs b/src/Finance/IBAN/Internal.hs
--- a/src/Finance/IBAN/Internal.hs
+++ b/src/Finance/IBAN/Internal.hs
@@ -115,9 +115,9 @@
     step (_,   True,   _ ) '!' = err "unexpected '!'"
     step (cnt, False,  xs) '!' = (cnt, True, xs)
     step (cnt, strict, xs)  c
-      | isDigit c              = (cnt*10 + digitToInt c, False, xs)
-      | c `elem` "nace"        = addElement xs condition cnt strict
-      | otherwise              = err $ "unexpected " ++ show c
+      | isDigit c               = (cnt*10 + digitToInt c, False, xs)
+      | elem c ("nace"::String) = addElement xs condition cnt strict
+      | otherwise               = err $ "unexpected " ++ show c
       where
         condition = case c of
                       'n' -> isDigit