diff --git a/Command/Info.hs b/Command/Info.hs
index d273c4a5b4..5ef3ffbb97 100644
--- a/Command/Info.hs
+++ b/Command/Info.hs
@@ -5,7 +5,7 @@
  - Licensed under the GNU AGPL version 3 or higher.
  -}
 
-{-# LANGUAGE BangPatterns, DeriveDataTypeable, PackageImports #-}
+{-# LANGUAGE BangPatterns, DeriveDataTypeable, PackageImports, OverloadedStrings #-}
 
 module Command.Info where
 
@@ -446,7 +446,7 @@ transfer_list = stat desc $ nojson $ lift $ do
 		, maybe (fromUUID $ transferUUID t) Remote.name $
 			M.lookup (transferUUID t) uuidmap
 		]
-	jsonify t i = object $ map (\(k, v) -> (packString k, v)) $
+	jsonify t i = object $
 		[ ("transfer", toJSON' (formatDirection (transferDirection t)))
 		, ("key", toJSON' (transferKey t))
 		, ("file", toJSON' (fromRawFilePath <$> afile))
diff --git a/Messages/JSON.hs b/Messages/JSON.hs
index 1f8a332f7a..7d9704e503 100644
--- a/Messages/JSON.hs
+++ b/Messages/JSON.hs
@@ -5,7 +5,7 @@
  - Licensed under the GNU AGPL version 3 or higher.
  -}
 
-{-# LANGUAGE OverloadedStrings, GADTs #-}
+{-# LANGUAGE OverloadedStrings, GADTs, CPP #-}
 
 module Messages.JSON (
 	JSONBuilder,
@@ -33,7 +33,12 @@ import Control.Applicative
 import qualified Data.Map as M
 import qualified Data.Vector as V
 import qualified Data.ByteString.Lazy as L
+#if MIN_VERSION_aeson(2,0,0)
+import qualified Data.Aeson.Key as AK
+import qualified Data.Aeson.KeyMap as HM
+#else
 import qualified Data.HashMap.Strict as HM
+#endif
 import System.IO
 import System.IO.Unsafe (unsafePerformIO)
 import Control.Concurrent
@@ -94,7 +99,7 @@ finalize o = addErrorMessage [] o
 
 addErrorMessage :: [String] -> Object -> Object
 addErrorMessage msg o =
-	HM.insertWith combinearray "error-messages" v o
+	HM.unionWith combinearray (HM.singleton "error-messages" v) o
   where
 	combinearray (Array new) (Array old) = Array (old <> new)
 	combinearray new _old = new
@@ -102,7 +107,7 @@ addErrorMessage msg o =
 
 note :: String -> JSONBuilder
 note _ Nothing = Nothing
-note s (Just (o, e)) = Just (HM.insertWith combinelines "note" (toJSON' s) o, e)
+note s (Just (o, e)) = Just (HM.unionWith combinelines (HM.singleton "note" (toJSON' s)) o, e)
   where
 	combinelines (String new) (String old) =
 		String (old <> "\n" <> new)
@@ -127,7 +132,13 @@ add v (Just (o, e)) = case j of
 	j = case v of
 		AesonObject ao -> Object ao
 		JSONChunk l -> object $ map mkPair l
-	mkPair (s, d) = (packString s, toJSON' d)
+	mkPair (s, d) =
+		(
+#if MIN_VERSION_aeson(2,0,0)
+		  AK.fromText $
+#endif
+		  packString s
+		, toJSON' d)
 add _ Nothing = Nothing
 
 complete :: JSONChunk v -> JSONBuilder
@@ -173,7 +184,13 @@ data ObjectMap a = ObjectMap { fromObjectMap :: M.Map String a }
 instance ToJSON' a => ToJSON' (ObjectMap a) where
 	toJSON' (ObjectMap m) = object $ map go $ M.toList m
 	  where
-		go (k, v) = (packString k, toJSON' v)
+		go (k, v) =
+			(
+#if MIN_VERSION_aeson(2,0,0)
+			  AK.fromText $
+#endif
+			  packString k
+			, toJSON' v)
 
 -- An item that a git-annex command acts on, and displays a JSON object about.
 data JSONActionItem a = JSONActionItem
diff --git a/Remote.hs b/Remote.hs
index b3207bd6d1..5e6658690f 100644
--- a/Remote.hs
+++ b/Remote.hs
@@ -5,7 +5,7 @@
  - Licensed under the GNU AGPL version 3 or higher.
  -}
 
-{-# LANGUAGE OverloadedStrings #-}
+{-# LANGUAGE OverloadedStrings, CPP #-}
 
 module Remote (
 	Remote,
@@ -63,6 +63,9 @@ module Remote (
 
 import Data.Ord
 import Data.String
+#if MIN_VERSION_aeson(2,0,0)
+import qualified Data.Aeson.Key as AK
+#endif
 import qualified Data.Map as M
 import qualified Data.Vector as V
 
@@ -239,11 +242,17 @@ prettyPrintUUIDsWith optfield header descm showval uuidvals = do
 			Nothing -> s
 			Just val -> val ++ ": " ++ s
 	jsonify hereu (u, optval) = object $ catMaybes
-		[ Just (packString "uuid", toJSON' (fromUUID u :: String))
-		, Just (packString "description", toJSON' $ finddescription u)
-		, Just (packString "here", toJSON' $ hereu == u)
+		[ Just ("uuid", toJSON' (fromUUID u :: String))
+		, Just ("description", toJSON' $ finddescription u)
+		, Just ("here", toJSON' $ hereu == u)
 		, case (optfield, optval) of
-			(Just field, Just val) -> Just (packString field, toJSON' val)
+			(Just field, Just val) -> Just
+				(
+#if MIN_VERSION_aeson(2,0,0)
+				  AK.fromText $
+#endif
+				  packString field
+				, toJSON' val)
 			_ -> Nothing
 		]
 
diff --git a/Types/MetaData.hs b/Types/MetaData.hs
index 100adbed05..7199763d73 100644
--- a/Types/MetaData.hs
+++ b/Types/MetaData.hs
@@ -7,6 +7,7 @@
 
 {-# LANGUAGE GeneralizedNewtypeDeriving #-}
 {-# LANGUAGE OverloadedStrings #-}
+{-# LANGUAGE CPP #-}
 
 module Types.MetaData (
 	MetaData(..),
@@ -51,6 +52,9 @@ import Utility.QuickCheck
 import Utility.Aeson
 import Types.UUID
 
+#if MIN_VERSION_aeson(2,0,0)
+import qualified Data.Aeson.Key as AK
+#endif
 import qualified Data.Text as T
 import qualified Data.Text.Encoding as E
 import qualified Data.Set as S
@@ -67,7 +71,13 @@ newtype MetaData = MetaData (M.Map MetaField (S.Set MetaValue))
 instance ToJSON' MetaData where
 	toJSON' (MetaData m) = object $ map go (M.toList m)
 	  where
-		go (MetaField f, s) = (CI.original f, toJSON' s)
+		go (MetaField f, s) =
+			(
+#if MIN_VERSION_aeson(2,0,0)
+			  AK.fromText $
+#endif
+			  CI.original f
+			, toJSON' s)
 
 instance FromJSON MetaData where
 	parseJSON (Object o) = do
diff --git a/Utility/Aeson.hs b/Utility/Aeson.hs
index c872bd14fc..c82bf35833 100644
--- a/Utility/Aeson.hs
+++ b/Utility/Aeson.hs
@@ -7,7 +7,7 @@
  - License: BSD-2-clause
  -}
 
-{-# LANGUAGE FlexibleInstances, TypeSynonymInstances #-}
+{-# LANGUAGE FlexibleInstances, TypeSynonymInstances, CPP #-}
 
 module Utility.Aeson (
 	module X,
@@ -17,7 +17,7 @@ module Utility.Aeson (
 	packByteString,
 ) where
 
-import Data.Aeson as X hiding (ToJSON, toJSON, encode)
+import Data.Aeson as X hiding (ToJSON, toJSON, encode, Key)
 import Data.Aeson hiding (encode)
 import qualified Data.Aeson
 import qualified Data.Text as T