diff --git a/ChangeLog.md b/ChangeLog.md
--- a/ChangeLog.md
+++ b/ChangeLog.md
@@ -1,5 +1,9 @@
 # Revision history for cborg-json
 
+## 0.2.3.0  -- 2021-10-31
+
+* Support for `aeson-2.0`, GHC 9.0, GHC 9.2, and `bytestring-0.11`.
+
 ## 0.2.2.0  -- 2019-12-29
 
 * Use `replicateM` to significantly speed up decoding. Now faster than Aeson!
diff --git a/cborg-json.cabal b/cborg-json.cabal
--- a/cborg-json.cabal
+++ b/cborg-json.cabal
@@ -1,5 +1,5 @@
 name:                cborg-json
-version:             0.2.2.0
+version:             0.2.3.0
 synopsis:            A library for encoding JSON as CBOR
 description:         This package implements the bijection between JSON and
                      CBOR defined in the CBOR specification, RFC 7049.
@@ -17,14 +17,20 @@
 extra-source-files:  ChangeLog.md
 cabal-version:       >=1.10
 tested-with:
-  GHC == 7.8.4, GHC == 7.10.3, GHC == 8.0.2, GHC == 8.2.2, GHC == 8.4.4, GHC == 8.6.5, GHC==8.8.1
+  GHC == 8.0.2,
+  GHC == 8.2.2,
+  GHC == 8.4.4,
+  GHC == 8.6.5,
+  GHC == 8.8.3,
+  GHC == 8.10.1,
+  GHC == 9.0.1
 
 library
   exposed-modules:     Codec.CBOR.JSON
   ghc-options:         -Wall
   build-depends:
-    base >=4.7 && < 4.14,
-    aeson >=0.7 && <1.5,
+    base >=4.7 && < 4.17,
+    aeson >=0.7 && <2.1,
     aeson-pretty >=0.8 && <0.9,
     unordered-containers >=0.2 && <0.3,
     scientific >=0.3 && <0.4,
@@ -51,11 +57,11 @@
   other-modules:
 
   build-depends:
-    base                    >= 4.6     && < 5.0,
+    base                    >= 4.6     && < 4.17,
     cborg                                      ,
     cborg-json                                 ,
     aeson                                      ,
-    bytestring              >= 0.10.4  && < 0.11,
+    bytestring              >= 0.10.4  && < 0.12,
     criterion               >= 1.0     && < 1.6,
     deepseq                 >= 1.0     && < 1.5,
     directory,
diff --git a/src/Codec/CBOR/JSON.hs b/src/Codec/CBOR/JSON.hs
--- a/src/Codec/CBOR/JSON.hs
+++ b/src/Codec/CBOR/JSON.hs
@@ -1,4 +1,5 @@
 {-# LANGUAGE BangPatterns #-}
+{-# LANGUAGE CPP          #-}
 
 module Codec.CBOR.JSON
  ( encodeValue
@@ -13,11 +14,17 @@
 import           Codec.CBOR.Decoding
 import           Data.Aeson                          ( Value(..) )
 import qualified Data.Aeson                          as Aeson
-import qualified Data.HashMap.Lazy                   as HM
 import           Data.Scientific                     as Scientific
 import qualified Data.Text                           as T
 import qualified Data.Vector                         as V
 
+#if MIN_VERSION_aeson(2,0,0)
+import qualified Data.Aeson.Key                      as K
+import qualified Data.Aeson.KeyMap                   as KM
+#else
+import qualified Data.HashMap.Lazy                   as HM
+#endif
+
 -- | Encode a JSON value into CBOR.
 encodeValue :: Value -> Encoding
 encodeValue (Object vs) = encodeObject vs
@@ -31,8 +38,18 @@
 
 encodeObject :: Aeson.Object -> Encoding
 encodeObject vs =
-    encodeMapLen (fromIntegral (HM.size vs))
- <> HM.foldrWithKey (\k v r -> encodeString k <> encodeValue v <> r) mempty vs
+     encodeMapLen (fromIntegral size)
+  <> foldrWithKey (\k v r -> encodeString' k <> encodeValue v <> r) mempty vs
+  where
+#if MIN_VERSION_aeson(2,0,0)
+    size = KM.size vs
+    foldrWithKey = KM.foldrWithKey
+    encodeString' = encodeString . K.toText
+#else
+    size = HM.size vs
+    foldrWithKey = HM.foldrWithKey
+    encodeString' = encodeString
+#endif
 
 encodeArray :: Aeson.Array -> Encoding
 encodeArray vs =
@@ -58,7 +75,7 @@
 
       TypeListLen      -> decodeListLen >>= decodeListN lenient
       TypeListLenIndef -> decodeListLenIndef >> decodeListIndef lenient []
-      TypeMapLen       -> decodeMapLen >>= flip (decodeMapN lenient) HM.empty
+      TypeMapLen       -> decodeMapLen >>= flip (decodeMapN lenient) mempty
 
       _           -> fail $ "unexpected CBOR token type for a JSON value: "
                          ++ show tkty
@@ -101,4 +118,10 @@
                  Bool   b | lenient -> return $ T.pack (show b)
                  _        -> fail "Could not decode map key type"
         !tv  <- decodeValue lenient
-        decodeMapN lenient (n-1) (HM.insert tk tv acc)
+        decodeMapN lenient (n-1) (insert tk tv acc)
+  where
+#if MIN_VERSION_aeson(2,0,0)
+    insert k v m = KM.insert (K.fromText k) v m
+#else
+    insert k v m = HM.insert k v m
+#endif