diff --git a/ChangeLog.md b/ChangeLog.md
--- a/ChangeLog.md
+++ b/ChangeLog.md
@@ -1,6 +1,6 @@
 # Revision history for aeson-gadt-th
 
-## 0.2.3
+## 0.2.4
 
 * Support for GHC 8.8
 
diff --git a/README.lhs b/README.lhs
--- a/README.lhs
+++ b/README.lhs
@@ -18,12 +18,12 @@
 >
 > import Data.Aeson
 > import Data.Aeson.GADT.TH
->
-> import Data.Dependent.Map (DMap, Some(..))
+> import Data.Dependent.Map (DMap)
 > import Data.Dependent.Sum (DSum)
 > import Data.Functor.Identity
 > import Data.GADT.Compare
 > import Data.GADT.Show.TH
+> import Data.Some (Some(..))
 >
 > data A :: * -> * where
 >   A_a :: A a
diff --git a/README.md b/README.md
--- a/README.md
+++ b/README.md
@@ -18,12 +18,12 @@
 >
 > import Data.Aeson
 > import Data.Aeson.GADT.TH
->
-> import Data.Dependent.Map (DMap, Some(..))
+> import Data.Dependent.Map (DMap)
 > import Data.Dependent.Sum (DSum)
 > import Data.Functor.Identity
 > import Data.GADT.Compare
 > import Data.GADT.Show.TH
+> import Data.Some (Some(..))
 >
 > data A :: * -> * where
 >   A_a :: A a
diff --git a/aeson-gadt-th.cabal b/aeson-gadt-th.cabal
--- a/aeson-gadt-th.cabal
+++ b/aeson-gadt-th.cabal
@@ -1,6 +1,6 @@
 cabal-version: 2.0
 name: aeson-gadt-th
-version: 0.2.3
+version: 0.2.4
 synopsis: Derivation of Aeson instances for GADTs
 category: JSON
 description: Template Haskell for generating ToJSON and FromJSON instances for GADTs. See <https://github.com/obsidiansystems/aeson-gadt-th/blob/master/README.md README.md> for examples.
@@ -11,7 +11,7 @@
 copyright: 2019 Obsidian Systems LLC
 build-type: Simple
 tested-with:
-  GHC  ==8.0.2 || ==8.2.2 || ==8.4.4 || ==8.6.5
+  GHC  ==8.0.2 || ==8.2.2 || ==8.4.4 || ==8.6.5 || == 8.8.3
 extra-source-files: README.md
                     ChangeLog.md
 
@@ -20,14 +20,16 @@
 
 library
   exposed-modules: Data.Aeson.GADT.TH
-  build-depends: base >= 4.8 && < 4.13
+  build-depends: base >= 4.8 && < 4.14
                , aeson >= 1.4 && < 1.5
                , containers >= 0.5 && < 0.7
-               , dependent-sum >= 0.6.1 && < 0.7
+               , dependent-sum >= 0.6.1 && < 0.8
                , transformers >= 0.5 && < 0.6
-               , template-haskell >= 2.11.0 && < 2.15
+               , template-haskell >= 2.11.0 && < 2.16
                , th-abstraction >= 0.3.1.0 && < 0.4
                , th-extras >= 0.0.0.4 && < 0.1
+  if impl(ghc < 8.2)
+    build-depends: dependent-sum < 0.6.2.2
   hs-source-dirs: src
   default-language: Haskell2010