diff --git a/mandrill.cabal b/mandrill.cabal
--- a/mandrill.cabal
+++ b/mandrill.cabal
@@ -1,5 +1,5 @@
 name:                mandrill
-version:             0.5.6.0
+version:             0.5.7.0
 synopsis:            Library for interfacing with the Mandrill JSON API
 description:         Pure Haskell client for the Mandrill JSON API
 license:             MIT
@@ -37,7 +37,7 @@
     , containers >= 0.5.0.0
     , bytestring >= 0.9.0
     , base64-bytestring >= 1.0.0.1
-    , text >= 1.0.0.0 && < 1.3
+    , text >= 1.0.0.0 && < 2.1
     , http-types >= 0.8.0
     , http-client >= 0.3.0
     , http-client-tls >= 0.2.0.0
diff --git a/src/Network/API/Mandrill.hs b/src/Network/API/Mandrill.hs
--- a/src/Network/API/Mandrill.hs
+++ b/src/Network/API/Mandrill.hs
@@ -122,7 +122,7 @@
 
 --------------------------------------------------------------------------------
 -- | Create a new template message (no HTML) with recipient addresses only.
--- This function is preferred when the template being used has the sender
+-- This function is preferred when the template being used has the sender 
 -- address and subject already configured in the Mandrill server.
 newTemplateMessage' :: [EmailAddress]
                     -- ^ Receivers email
diff --git a/src/Network/API/Mandrill/Types.hs b/src/Network/API/Mandrill/Types.hs
--- a/src/Network/API/Mandrill/Types.hs
+++ b/src/Network/API/Mandrill/Types.hs
@@ -31,6 +31,7 @@
 import           Data.Foldable
 import           Data.Traversable
 #endif
+import qualified Data.HashMap.Strict           as H
 import           Data.Monoid
 import qualified Data.Text                     as T
 import qualified Data.Text.Encoding            as TL