diff --git a/happstack-data.cabal b/happstack-data.cabal
--- a/happstack-data.cabal
+++ b/happstack-data.cabal
@@ -1,5 +1,5 @@
 Name:               happstack-data
-Version:            0.5.0.2
+Version:            0.5.0.3
 License:            BSD3
 License-File:       COPYING
 Author:             Happstack team, HAppS LLC
@@ -56,7 +56,7 @@
                       containers,
                       happstack-util >= 0.5 && < 0.6, 
                       HaXml >= 1.13 && < 1.14,
-                      mtl,
+                      mtl >= 1.1 && < 2.1,
                       pretty,
                       syb-with-class >= 0.5,
                       syb-with-class-instances-text,