diff --git a/HTF.cabal b/HTF.cabal
--- a/HTF.cabal
+++ b/HTF.cabal
@@ -1,5 +1,5 @@
 Name:             HTF
-Version:          0.5.0.1
+Version:          0.6.0.0
 License:          LGPL
 License-File:     LICENSE
 Copyright:        (c) 2005-2010 Stefan Wehr
@@ -52,7 +52,7 @@
                     containers == 0.3.*,
                     process == 1.0.*,
                     directory == 1.0.*,
-                    mtl == 1.1.*,
+                    mtl >= 1.1 && < 2.1,
                     pretty == 1.0.*
   Exposed-Modules:
     Test.Framework