diff --git a/CHANGELOG.md b/CHANGELOG.md
index 578d08a..b40903b 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,16 +1,21 @@
 # Changelog
 
+### v0.4.0
+
+Update dependencies, in particular, aeson v2.
+
+
 ### v0.3.11
 
-- Add CHANGELOG and README to the stack tarball
+Add CHANGELOG and README to the stack tarball.
 
 ### v0.3.10
 
-- Added missing test files to the stack tarball
+Added missing test files to the stack tarball.
 
 ### v0.3.9
 
-- Adjusted version ranges for test dependencies
+Adjusted version ranges for test dependencies.
 
 ### v0.3.8
 
@@ -52,6 +57,7 @@
 - Added `listRelative` and it's flipped relative
 - Updated dependencies
 
+
 ### v0.2.1
 
 - Fix order of the `list` function parameters
@@ -62,6 +68,7 @@
 - Add more `Utilities` (sequence utils, metadata helpers, etc.)
 - Clean up code
 
+
 ### v0.1.3
 
 - Fix `Contrib.prefixDirname` which didn't change `pathToRoot` and `parentPath` like it should
diff --git a/package.yaml b/package.yaml
index 9c4140a..29a1f14 100644
--- a/package.yaml
+++ b/package.yaml
@@ -1,5 +1,5 @@
 name: shikensu
-version: 0.3.11
+version: 0.4.0
 maintainer: Steven Vandevelde <icid.asset@gmail.com>
 category: Filesystem
 
@@ -17,9 +17,9 @@ default-extensions:
 
 
 dependencies:
-  - aeson == 1.*
+  - aeson == 2.*
   - base >= 4.9 && < 5
-  - bytestring == 0.10.*
+  - bytestring >= 0.10 && < 0.12
   - directory == 1.*
   - filepath == 1.*
   - flow == 1.*
diff --git a/src/Shikensu.hs b/src/Shikensu.hs
index a0548be..de2483a 100644
--- a/src/Shikensu.hs
+++ b/src/Shikensu.hs
@@ -20,7 +20,7 @@ import Shikensu.Internal.Types
 import Shikensu.Internal.Utilities
 import System.FilePath
 
-import qualified Data.HashMap.Strict as HashMap (empty)
+import qualified Data.Aeson.KeyMap as KeyMap (empty)
 import qualified Data.List as List (concatMap, map, zip)
 import qualified System.Directory as Dir (canonicalizePath)
 import qualified System.FilePath.Glob as Glob (compile, globDir1)
@@ -115,7 +115,7 @@ Example definition, given:
 >     , workingDirname = "example"
 >
 >     , content = Nothing
->     , metadata = HashMap.empty
+>     , metadata = KeyMap.empty
 >     , parentPath = "../"
 >     , pathToRoot = "../../"
 >     }
@@ -140,7 +140,7 @@ makeDefinition rootDirname pattern absolutePath =
 
             -- Additional properties
             , content         = Nothing
-            , metadata        = HashMap.empty
+            , metadata        = KeyMap.empty
             , parentPath      = compileParentPath $ takeDirName theLocalPath
             , pathToRoot      = compilePathToRoot $ takeDirName theLocalPath
             }
diff --git a/src/Shikensu/Contrib.hs b/src/Shikensu/Contrib.hs
index c693ac5..3afd219 100644
--- a/src/Shikensu/Contrib.hs
+++ b/src/Shikensu/Contrib.hs
@@ -36,7 +36,7 @@ import Shikensu.Internal.Utilities (compileParentPath, compilePathToRoot)
 import Shikensu.Metadata (transposeToMetadata)
 import System.FilePath (FilePath, combine)
 
-import qualified Data.HashMap.Strict as HashMap (empty, union)
+import qualified Data.Aeson.KeyMap as KeyMap (empty, union)
 
 
 {-| Clear metadata.
@@ -50,7 +50,7 @@ clearMetadata =
 
 clearMetadataDef :: Definition -> Definition
 clearMetadataDef def =
-    def { metadata = HashMap.empty }
+    def { metadata = KeyMap.empty }
 
 
 
@@ -87,7 +87,7 @@ copyPropsToMetadata =
 copyPropsToMetadataDef :: Definition -> Definition
 copyPropsToMetadataDef def =
     def
-        { metadata = HashMap.union (transposeToMetadata def) (metadata def) }
+        { metadata = KeyMap.union (transposeToMetadata def) (metadata def) }
 
 
 
@@ -112,7 +112,7 @@ insertMetadata a =
 
 insertMetadataDef :: Metadata -> Definition -> Definition
 insertMetadataDef given def =
-    def { metadata = HashMap.union given (metadata def) }
+    def { metadata = KeyMap.union given (metadata def) }
 
 
 
diff --git a/src/Shikensu/Internal/Types.hs b/src/Shikensu/Internal/Types.hs
index 12b062d..315c354 100644
--- a/src/Shikensu/Internal/Types.hs
+++ b/src/Shikensu/Internal/Types.hs
@@ -5,11 +5,12 @@
 module Shikensu.Internal.Types where
 
 import Data.Aeson ((.=), toJSON)
+import Data.Aeson.KeyMap (KeyMap)
 import Data.ByteString (ByteString)
 import Data.Monoid ((<>))
 import System.FilePath (joinPath)
 
-import qualified Data.Aeson as Aeson (Object, ToJSON, object)
+import qualified Data.Aeson as Aeson (ToJSON, Value, object)
 
 
 {-| A file definition, along with some additional properties.
@@ -49,7 +50,7 @@ instance Aeson.ToJSON Definition where
 
 
 type Dictionary = [Definition]
-type Metadata = Aeson.Object
+type Metadata = KeyMap Aeson.Value
 
 
 
diff --git a/src/Shikensu/Metadata.hs b/src/Shikensu/Metadata.hs
index 382e839..0f3d14d 100644
--- a/src/Shikensu/Metadata.hs
+++ b/src/Shikensu/Metadata.hs
@@ -10,7 +10,7 @@ import Flow
 import Shikensu.Internal.Types
 
 import qualified Data.Aeson as Aeson (FromJSON, Result(..), ToJSON, fromJSON, toJSON)
-import qualified Data.HashMap.Strict as HashMap (empty)
+import qualified Data.Aeson.KeyMap as KeyMap (empty, fromList)
 
 
 {-| Transpose metadata.
@@ -22,15 +22,15 @@ which implements the Aeson.FromJSON instance.
 >     Example { some :: Text }
 >     deriving (Generic, FromJSON)
 >
-> hashMap     = HashMap.fromList [ ("some", "metadata") ]
+> keyMap      = KeyMap.fromList [ ("some", "metadata") ]
 > defaultEx   = Example { some = "default" }
-> example     = transposeMetadata hashMap defaultEx :: Example
+> example     = transposeMetadata keyMap defaultEx :: Example
 
 -}
 transposeMetadata :: Aeson.FromJSON a => Metadata -> a -> a
-transposeMetadata hashMap fallback =
+transposeMetadata keyMap fallback =
     let
-        result = hashMap
+        result = keyMap
             |> Aeson.toJSON
             |> Aeson.fromJSON :: Aeson.FromJSON b => Aeson.Result b
     in
@@ -50,4 +50,4 @@ transposeToMetadata generic =
     in
         case result of
             Aeson.Success x -> x
-            Aeson.Error _   -> HashMap.empty
+            Aeson.Error _   -> KeyMap.empty
diff --git a/src/Shikensu/Utilities.hs b/src/Shikensu/Utilities.hs
index 9bba193..8cc2d90 100644
--- a/src/Shikensu/Utilities.hs
+++ b/src/Shikensu/Utilities.hs
@@ -14,7 +14,8 @@ import Flow
 import Shikensu.Internal.Types
 
 import qualified Data.Aeson as Json (Object, Result(..), encode)
-import qualified Data.HashMap.Strict as HashMap (lookup)
+import qualified Data.Aeson.KeyMap as KeyMap (lookup)
+import qualified Data.Aeson.Key as Key (fromText)
 import qualified Data.List as List (unzip, zip)
 import qualified Data.Text as Text (unpack)
 import qualified Data.Text.Lazy as Lazy.Text (unpack)
@@ -72,7 +73,8 @@ lsequence list =
 -}
 (~>) :: (FromJSON a, ToJSON a) => Metadata -> Text -> Maybe a
 (~>) obj key =
-    HashMap.lookup key obj
+    obj
+        |> KeyMap.lookup (Key.fromText key)
         |> fmap fromJSON
         |> fmap fromJSONResult
 
diff --git a/stack.yaml b/stack.yaml
index 68e0c1c..5ff4c7a 100644
--- a/stack.yaml
+++ b/stack.yaml
@@ -1 +1,3 @@
-resolver: nightly-2020-09-19
+resolver: nightly-2021-12-26
+extra-deps:
+  - aeson-2.0.2.0
diff --git a/stack.yaml.lock b/stack.yaml.lock
index d5c6b98..4ea8f7c 100644
--- a/stack.yaml.lock
+++ b/stack.yaml.lock
@@ -3,10 +3,17 @@
 # For more information, please see the documentation at:
 #   https://docs.haskellstack.org/en/stable/lock_files
 
-packages: []
+packages:
+- completed:
+    hackage: aeson-2.0.2.0@sha256:bb41f39762d6f755431097ce0fa88d817108036e7f1c1ec06fd5990230860c76,6343
+    pantry-tree:
+      size: 37910
+      sha256: 5303edc2f9516c7999c21fbfb218ad180dd91c2ceea570f8bc54818ea9ec1692
+  original:
+    hackage: aeson-2.0.2.0
 snapshots:
 - completed:
-    size: 531498
-    url: https://raw.githubusercontent.com/commercialhaskell/stackage-snapshots/master/nightly/2020/9/19.yaml
-    sha256: e39020cba3f67726df5d467ee7ddda6887f4be3a07fe3ece0eb2bdef801138c3
-  original: nightly-2020-09-19
+    size: 621066
+    url: https://raw.githubusercontent.com/commercialhaskell/stackage-snapshots/master/nightly/2021/12/26.yaml
+    sha256: b0ce4f7d53851f1e875b52df2a8a20d77c65883d8350b997580ded88eec0a4b2
+  original: nightly-2021-12-26
diff --git a/tests/Test/Contrib.hs b/tests/Test/Contrib.hs
index 2c79df3..6e7b5c4 100644
--- a/tests/Test/Contrib.hs
+++ b/tests/Test/Contrib.hs
@@ -11,9 +11,10 @@ import Test.Tasty
 import Test.Tasty.HUnit
 
 import qualified Data.Aeson.Types as Aeson (Value(..))
+import qualified Data.Aeson.Key as Key (fromText)
 import qualified Data.ByteString as B (empty)
 import qualified Data.ByteString.Char8 as BS (intercalate, pack)
-import qualified Data.HashMap.Strict as HashMap (fromList, lookup)
+import qualified Data.Aeson.KeyMap as KeyMap (fromList, lookup)
 import qualified Data.List as List (head, reverse)
 import qualified Data.Text as Text (pack, unpack)
 import qualified Data.Text.Encoding as Text (decodeUtf8, encodeUtf8)
@@ -100,16 +101,16 @@ testExclude =
 testMetadata :: TestTree
 testMetadata =
     let
-        keyA        = Text.pack "title"
+        keyA        = Key.fromText (Text.pack "title")
         valueA      = Aeson.String (Text.pack "Hello world!")
 
-        keyB        = Text.pack "hello"
+        keyB        = Key.fromText (Text.pack "hello")
         valueB      = Aeson.String (Text.pack "Guardian.")
 
-        keyC        = Text.pack "removed"
+        keyC        = Key.fromText (Text.pack "removed")
         valueC      = Aeson.String (Text.pack "Me.")
 
-        keyBase     = Text.pack "basename"
+        keyBase     = Key.fromText (Text.pack "basename")
         valueBase   = Aeson.String (Text.pack "example")
 
         -- 1. Insert C
@@ -117,19 +118,19 @@ testMetadata =
         -- 3. Insert B
         dictionary = fmap
             ( id
-                .> Contrib.insertMetadata   (HashMap.fromList [ (keyC, valueC) ])
-                .> Contrib.replaceMetadata  (HashMap.fromList [ (keyA, valueA) ])
+                .> Contrib.insertMetadata   (KeyMap.fromList [ (keyC, valueC) ])
+                .> Contrib.replaceMetadata  (KeyMap.fromList [ (keyA, valueA) ])
                 .> Contrib.copyPropsToMetadata
-                .> Contrib.insertMetadata   (HashMap.fromList [ (keyB, valueB) ])
+                .> Contrib.insertMetadata   (KeyMap.fromList [ (keyB, valueB) ])
             )
             example_md
 
         definition          = fmap (List.reverse .> List.head) dictionary
 
-        lookupTitle     def = HashMap.lookup keyA (Shikensu.metadata def)
-        lookupHello     def = HashMap.lookup keyB (Shikensu.metadata def)
-        lookupRemoved   def = HashMap.lookup keyC (Shikensu.metadata def)
-        lookupBasename  def = HashMap.lookup keyBase (Shikensu.metadata def)
+        lookupTitle     def = KeyMap.lookup keyA (Shikensu.metadata def)
+        lookupHello     def = KeyMap.lookup keyB (Shikensu.metadata def)
+        lookupRemoved   def = KeyMap.lookup keyC (Shikensu.metadata def)
+        lookupBasename  def = KeyMap.lookup keyBase (Shikensu.metadata def)
     in
         testGroup
             "Metadata"
diff --git a/tests/Test/Utilities.hs b/tests/Test/Utilities.hs
index 7c4215f..26ca727 100644
--- a/tests/Test/Utilities.hs
+++ b/tests/Test/Utilities.hs
@@ -10,7 +10,7 @@ import Test.Helpers
 import Test.Tasty
 import Test.Tasty.HUnit
 
-import qualified Data.HashMap.Strict as HashMap (singleton)
+import qualified Data.Aeson.KeyMap as KeyMap (singleton)
 import qualified Data.List as List (head)
 import qualified Data.Tuple as Tuple (fst)
 import qualified Shikensu.Contrib as Contrib
@@ -54,7 +54,7 @@ testMetadataAccessors =
         definition =
             "."
                 |> define thePattern
-                |> fmap (Contrib.insertMetadataDef $ HashMap.singleton "a" "Hi!")
+                |> fmap (Contrib.insertMetadataDef $ KeyMap.singleton "a" "Hi!")
 
         resultExisting =
             fmap (\d -> metadata d ~> "a" :: Maybe String) definition