diff --git a/CHANGES b/CHANGES
--- a/CHANGES
+++ b/CHANGES
@@ -53,3 +53,7 @@
 Version 0.4.0.1: 23 March 2012
 
   * Remove broken links from documentation
+
+Version 0.4.0.2: 10 April 2012
+
+  * Bump 'mtl' upper bound to allow mtl-2.1
diff --git a/unbound.cabal b/unbound.cabal
--- a/unbound.cabal
+++ b/unbound.cabal
@@ -1,5 +1,5 @@
 name:           unbound
-version:        0.4.0.1
+version:        0.4.0.2
 license:        BSD3
 license-file:   LICENSE
 build-type:     Simple
@@ -31,7 +31,7 @@
 Library
   build-depends: base >= 4.3 && < 5,
                  RepLib >= 0.5.1 && < 0.6,
-                 mtl >= 2.0 && < 2.1, transformers >= 0.2.2.0 && < 0.2.3,
+                 mtl >= 2.0 && < 2.2, transformers >= 0.2.2.0 && < 0.4,
                  containers >= 0.3 && < 0.5
   exposed-modules:
     Unbound.LocallyNameless,