diff --git a/src/Tesla/Car.hs b/src/Tesla/Car.hs
--- a/src/Tesla/Car.hs
+++ b/src/Tesla/Car.hs
@@ -47,6 +47,7 @@
 import           Control.Monad.Reader    (MonadReader, ReaderT (..), asks, runReaderT)
 import           Data.Aeson              (FromJSON (..), Options (..), Result (..), Value (..), decode, defaultOptions,
                                           encode, fieldLabelModifier, fromJSON, genericParseJSON, withObject, (.:))
+import           Data.Aeson.Key          (Key)
 import           Data.Aeson.Lens         (_Bool, _Integer, _String, key, values)
 import qualified Data.ByteString.Lazy    as BL
 import           Data.Foldable           (fold)
@@ -261,7 +262,7 @@
   pure $ parseOne rb SC "superchargers" <> parseOne rb DC "destination_charging"
 
     where
-      parseOne :: FromJSON a => Value -> (a -> Charger) -> Text -> [Charger]
+      parseOne :: FromJSON a => Value -> (a -> Charger) -> Key -> [Charger]
       parseOne rb f k =  let rs = traverse fromJSON (rb ^.. key "response" . key k . values) in
                            f <$> case rs of
                                    Error e   -> error e
diff --git a/src/Tesla/Car/Command.hs b/src/Tesla/Car/Command.hs
--- a/src/Tesla/Car/Command.hs
+++ b/src/Tesla/Car/Command.hs
@@ -86,7 +86,7 @@
 mkCommand s u = do
   let m = mkName "m"
   pure [
-    SigD (mkName s) (ForallT [PlainTV m] [AppT (ConT (mkName "MonadIO")) (VarT m)]
+    SigD (mkName s) (ForallT [PlainTV m inferredSpec] [AppT (ConT (mkName "MonadIO")) (VarT m)]
                      (AppT (AppT (ConT (mkName "Car")) (VarT m)) (ConT (mkName "CommandResponse")))),
     FunD (mkName s) [Clause [] (NormalB expr) []]]
   where expr = LamE [] (AppE (VarE (mkName "runCmd'")) (LitE (StringL u)))
diff --git a/tesla.cabal b/tesla.cabal
--- a/tesla.cabal
+++ b/tesla.cabal
@@ -1,13 +1,13 @@
 cabal-version: 1.12
 
--- This file has been generated from package.yaml by hpack version 0.34.5.
+-- This file has been generated from package.yaml by hpack version 0.34.7.
 --
 -- see: https://github.com/sol/hpack
 --
--- hash: 4b13596c9991ae6a3294f3b1f6ac466fe9c7bf0a81479506fbd15c939f169d02
+-- hash: 7dc4bf02fba7a28f00be8a80d8cffd2b74a70a07a4be1472703b2aacc4af947e
 
 name:           tesla
-version:        0.5.0.0
+version:        0.5.1.0
 synopsis:       Tesla API client.
 description:    Please see the README on GitHub at <https://github.com/dustin/tesla#readme>
 category:       Web
@@ -59,7 +59,7 @@
       NamedFieldPuns
   ghc-options: -Wall
   build-depends:
-      aeson >=1.4.5 && <1.6
+      aeson ==2.0.*
     , base >=4.7 && <5
     , base64-bytestring
     , bytestring ==0.10.*
@@ -71,7 +71,7 @@
     , generic-deriving >=1.12 && <1.15
     , http-client
     , lens >=4.17 && <5.2
-    , lens-aeson >=1.0 && <1.2
+    , lens-aeson ==1.2.*
     , memory
     , monad-logger
     , mtl ==2.2.*
@@ -100,7 +100,7 @@
   ghc-options: -threaded -rtsopts -with-rtsopts=-N
   build-depends:
       HUnit
-    , aeson >=1.4.5 && <1.6
+    , aeson ==2.0.*
     , base >=4.7 && <5
     , base64-bytestring
     , bytestring ==0.10.*
@@ -112,7 +112,7 @@
     , generic-deriving >=1.12 && <1.15
     , http-client
     , lens >=4.17 && <5.2
-    , lens-aeson >=1.0 && <1.2
+    , lens-aeson ==1.2.*
     , memory
     , monad-logger
     , mtl ==2.2.*