diff --git a/postmark.cabal b/postmark.cabal
--- a/postmark.cabal
+++ b/postmark.cabal
@@ -1,5 +1,5 @@
 Name:               postmark
-Version:            0.2.6
+Version:            0.2.7
 License:            BSD3
 License-File:       LICENSE
 Author:             Mark Hibberd <mark@hibberd.id.au>
@@ -26,10 +26,10 @@
 Library
   Build-Depends:
                     base                            >= 3 && < 5
-                    , aeson                         >= 0.6 && < 1.4
+                    , aeson                         >= 0.6 && < 2
                     , attoparsec                    >= 0.10 && < 0.14
                     , bytestring                    >= 0.9 && < 0.11
-                    , containers                    >= 0.4 && < 0.6
+                    , containers                    >= 0.4 && < 0.7
                     , http-types                    >= 0.6 && < 1
                     , text                          >= 0.11 && < 1.3
                     , network-api-support           >= 0.3.0 && < 0.4
