diff --git a/CHANGELOG.md b/CHANGELOG.md
new file mode 100644
--- /dev/null
+++ b/CHANGELOG.md
@@ -0,0 +1,17 @@
+# Changelog for gray-extended
+
+1.5.9 Simplified cabal file again.
+
+1.5.8 Simplified cabal file.
+
+1.5.7 Simplified nix configuration.
+
+1.5.6 Corrected copyright info.
+
+1.5.5 Revamped to work with Nix + cabal-install
+
+1.5.4 Revamped to work with Nix + Stack.
+
+1.5.3 Upgrade to work with Stack 1.9.3
+
+## Unreleased changes
diff --git a/ChangeLog.md b/ChangeLog.md
deleted file mode 100644
--- a/ChangeLog.md
+++ /dev/null
@@ -1,15 +0,0 @@
-# Changelog for gray-extended
-
-1.5.8 Simplified cabal file.
-
-1.5.7 Simplified nix configuration.
-
-1.5.6 Corrected copyright info.
-
-1.5.5 Revamped to work with Nix + cabal-install
-
-1.5.4 Revamped to work with Nix + Stack.
-
-1.5.3 Upgrade to work with Stack 1.9.3
-
-## Unreleased changes
diff --git a/LICENSE b/LICENSE
--- a/LICENSE
+++ b/LICENSE
@@ -1,4 +1,4 @@
-Copyright Amy de Buitléir (c) 2010-2019
+Copyright (c) 2010-2021, Amy de Buitléir
 
 All rights reserved.
 
diff --git a/Setup.hs b/Setup.hs
deleted file mode 100644
--- a/Setup.hs
+++ /dev/null
@@ -1,2 +0,0 @@
-import Distribution.Simple
-main = defaultMain
diff --git a/gray-extended.cabal b/gray-extended.cabal
--- a/gray-extended.cabal
+++ b/gray-extended.cabal
@@ -1,41 +1,48 @@
-cabal-version:       >=1.10
+cabal-version:      2.4
+name:               gray-extended
+version:            1.5.9
+synopsis:           Gray encoding schemes
+description:
+  Please see the README on GitHub at <https://github.com/mhwombat/gray-extended#readme>
+homepage:           https://github.com/mhwombat/gray-extended
+bug-reports:        https://github.com/mhwombat/gray-extended/issues
+license:            BSD-3-Clause
+license-file:       LICENSE
+author:             Amy de Buitléir
+maintainer:         amy@nualeargais.ie
+copyright:          2010-2021 Amy de Buitléir
+category:           Math
+extra-source-files:
+  CHANGELOG.md
+  README.md
 
-name:                gray-extended
-version:             1.5.8
-synopsis:            Gray encoding schemes
--- description:
-homepage:            https://github.com/mhwombat/gray-extended
-bug-reports:         https://github.com/mhwombat/gray-extended/issues
-license:             BSD3
-license-file:        LICENSE
-author:              Amy de Buitléir
-maintainer:          amy@nualeargais.ie
-copyright:           2010-2019 Amy de Buitléir
-category:            Math
-build-type:          Simple
-extra-source-files:  ChangeLog.md, README.md
+source-repository head
+  type:     git
+  location: https://github.com/mhwombat/gray-extended
 
+common common-stuff
+  default-language: Haskell2010
+
 library
-  exposed-modules:     Codec.Gray
-  other-modules:       Paths_gray_extended
-  -- other-extensions:
-  build-depends:       base >=4.7 && <5
-  hs-source-dirs:      src
-  default-language:    Haskell2010
+  import:          common-stuff
+  hs-source-dirs:  src
+  exposed-modules: Codec.Gray
+  other-modules:   Paths_gray_extended
+  autogen-modules: Paths_gray_extended
+  ghc-options:     -Wall -Wunused-packages
+  build-depends:   base >=4.7 && <5
 
 test-suite gray-extended-test
-  type:                exitcode-stdio-1.0
-  main-is:             TestMain.hs
-  other-modules:
-      Codec.GrayQC
-      Paths_gray_extended
-  hs-source-dirs:      test
-  ghc-options:         -threaded -rtsopts -with-rtsopts=-N
+  import:         common-stuff
+  type:           exitcode-stdio-1.0
+  hs-source-dirs: test
+  main-is:        TestMain.hs
+  other-modules:  Codec.GrayQC
+  ghc-options:
+    -threaded -rtsopts -with-rtsopts=-N -Wall -Wunused-packages
   build-depends:
-      QuickCheck
-    , base >=4.7 && <5
+    , base
     , gray-extended
+    , QuickCheck
     , test-framework
     , test-framework-quickcheck2
-  default-language:    Haskell2010
-
diff --git a/src/Codec/Gray.hs b/src/Codec/Gray.hs
--- a/src/Codec/Gray.hs
+++ b/src/Codec/Gray.hs
@@ -1,7 +1,7 @@
 ------------------------------------------------------------------------
 -- |
 -- Module      :  Codec.Gray
--- Copyright   :  (c) Amy de Buitléir 2011-2019
+-- Copyright   :  (c) 2011-2021 Amy de Buitléir
 -- License     :  BSD-style
 -- Maintainer  :  amy@nualeargais.ie
 -- Stability   :  experimental