diff --git a/unamb.cabal b/unamb.cabal
--- a/unamb.cabal
+++ b/unamb.cabal
@@ -1,5 +1,5 @@
 Name:                unamb
-Version:             0.1.0
+Version:             0.1.1
 Cabal-Version:       >= 1.2
 Synopsis:            Unambiguous choice
 Category:            Concurrency, Data, Other
@@ -30,7 +30,7 @@
 Library
   hs-Source-Dirs:      src
   Extensions:
-  Build-Depends:       base
+  Build-Depends:       base >= 4
   Exposed-Modules:     
                        Data.Unamb
   ghc-options:         -Wall