diff --git a/.ghci b/.ghci
--- a/.ghci
+++ b/.ghci
@@ -3,3 +3,4 @@
 :set -isrc
 :set -itest/suite
 :set -hide-package MonadCatchIO-mtl
+:set -hide-package monads-tf
diff --git a/heist.cabal b/heist.cabal
--- a/heist.cabal
+++ b/heist.cabal
@@ -1,5 +1,5 @@
 name:           heist
-version:        0.13.0.4
+version:        0.13.0.5
 synopsis:       An Haskell template system supporting both HTML5 and XML.
 description:
     Heist is a powerful template system that supports both HTML5 and XML.
@@ -139,7 +139,7 @@
 
   build-depends:
     MonadCatchIO-transformers  >= 0.2.1   && < 0.4,
-    aeson                      >= 0.6     && < 0.7,
+    aeson                      >= 0.6     && < 0.8,
     attoparsec                 >= 0.10    && < 0.12,
     base                       >= 4       && < 5,
     blaze-builder              >= 0.2     && < 0.4,
diff --git a/src/Heist/Splices/Json.hs b/src/Heist/Splices/Json.hs
--- a/src/Heist/Splices/Json.hs
+++ b/src/Heist/Splices/Json.hs
@@ -8,7 +8,6 @@
 ------------------------------------------------------------------------------
 import           Control.Monad.Reader
 import           Data.Aeson
-import           Data.Attoparsec.Number
 import qualified Data.ByteString.Char8       as S
 import qualified Data.ByteString.Lazy.Char8  as L
 import qualified Data.HashMap.Strict         as Map
@@ -86,7 +85,7 @@
 
 
 ------------------------------------------------------------------------------
-numToText :: Number -> Text
+numToText :: ToJSON a => a -> Text
 numToText = T.decodeUtf8 . S.concat . L.toChunks . encode
 
 
diff --git a/test/heist-testsuite.cabal b/test/heist-testsuite.cabal
--- a/test/heist-testsuite.cabal
+++ b/test/heist-testsuite.cabal
@@ -14,7 +14,7 @@
     test-framework             >= 0.6      && <0.7,
     test-framework-hunit       >= 0.2.7    && <0.3,
     test-framework-quickcheck2 >= 0.2.12.1 && <0.3,
-    aeson                      >= 0.6     && < 0.7,
+    aeson                      >= 0.6     && < 0.8,
     attoparsec                 >= 0.10    && < 0.12,
     base                       >= 4       && < 5,
     blaze-builder              >= 0.2     && < 0.4,
@@ -54,7 +54,7 @@
 
     -- Copied from regular dependencies:
 
-    aeson                      >= 0.6     && < 0.7,
+    aeson                      >= 0.6     && < 0.8,
     attoparsec                 >= 0.10    && < 0.12,
     base                       >= 4       && < 5,
     blaze-builder              >= 0.2     && < 0.4,