diff --git a/forest.cabal b/forest.cabal
--- a/forest.cabal
+++ b/forest.cabal
@@ -1,5 +1,5 @@
 name:           forest
-version:        0.1
+version:        0.1.1.1
 synopsis:       Tree and Forest types
 license:        MPL-2.0
 license-file:   LICENSE
@@ -24,7 +24,7 @@
     Data.Tree.Forest
 
   build-depends:
-    aeson >= 0.2 && < 1.2,
+    aeson >= 0.2 && < 1.3,
     base >= 4.2 && < 5,
     deepseq >= 1.1 && < 2,
     hashable >= 1.2 && < 2,
diff --git a/src/Data/Tree/Forest.hs b/src/Data/Tree/Forest.hs
--- a/src/Data/Tree/Forest.hs
+++ b/src/Data/Tree/Forest.hs
@@ -54,6 +54,9 @@
                      , parseJSON
                      , toJSON
                      )
+#if MIN_VERSION_aeson(1, 0, 0)
+import           Data.Aeson.Types (FromJSONKey, ToJSONKey)
+#endif
 
 
 -- base ----------------------------------------------------------------------
@@ -285,6 +288,18 @@
 
 
 ------------------------------------------------------------------------------
+instance (FromJSON s, FromJSON a, FromJSON (f (Tree f s a))) =>
+    FromJSON (Tree f s a)
+  where
+    parseJSON (Object o) = msum
+        [ Node <$> o .: "value" <*> o .: "children"
+        , Leaf <$> o .: "value"
+        ]
+    parseJSON _ = empty
+    {-# INLINE parseJSON #-}
+
+
+------------------------------------------------------------------------------
 instance (ToJSON s, ToJSON a, ToJSON (f (Tree f s a))) =>
     ToJSON (Tree f s a)
   where
@@ -298,19 +313,17 @@
     {-# INLINE toJSON #-}
 
 
+#if MIN_VERSION_aeson(1, 0, 0)
 ------------------------------------------------------------------------------
-instance (FromJSON s, FromJSON a, FromJSON (f (Tree f s a))) =>
-    FromJSON (Tree f s a)
-  where
-    parseJSON (Object o) = msum
-        [ Node <$> o .: "value" <*> o .: "children"
-        , Leaf <$> o .: "value"
-        ]
-    parseJSON _ = empty
-    {-# INLINE parseJSON #-}
+instance FromJSON (Tree f s a) => FromJSONKey (Tree f s a)
 
 
 ------------------------------------------------------------------------------
+instance ToJSON (Tree f s a) => ToJSONKey (Tree f s a)
+
+
+#endif
+------------------------------------------------------------------------------
 instance Eq1 f => Eq2 (Tree f) where
     liftEq2 _ eqa (Leaf a) (Leaf b) = eqa a b
     liftEq2 eqs eqa (Node s ts) (Node t tt) = and
@@ -566,6 +579,14 @@
 
 
 ------------------------------------------------------------------------------
+instance (FromJSON s, FromJSON a, FromJSON (f (Tree f s a))) =>
+    FromJSON (Forest f s a)
+  where
+    parseJSON = fmap Forest . parseJSON
+    {-# INLINE parseJSON #-}
+
+
+------------------------------------------------------------------------------
 instance (ToJSON s, ToJSON a, ToJSON (f (Tree f s a))) =>
     ToJSON (Forest f s a)
   where
@@ -573,14 +594,16 @@
     {-# INLINE toJSON #-}
 
 
+#if MIN_VERSION_aeson(1, 0, 0)
 ------------------------------------------------------------------------------
-instance (FromJSON s, FromJSON a, FromJSON (f (Tree f s a))) =>
-    FromJSON (Forest f s a)
-  where
-    parseJSON = fmap Forest . parseJSON
-    {-# INLINE parseJSON #-}
+instance FromJSON (Forest f s a) => FromJSONKey (Forest f s a)
 
 
+------------------------------------------------------------------------------
+instance ToJSON (Forest f s a) => ToJSONKey (Forest f s a)
+
+
+#endif
 ------------------------------------------------------------------------------
 instance Eq1 f => Eq2 (Forest f) where
     liftEq2 eqs eqa (Forest ts) (Forest tt) = liftEq (liftEq2 eqs eqa) ts tt