diff --git a/Data/EnumMap.hs b/Data/EnumMap.hs
--- a/Data/EnumMap.hs
+++ b/Data/EnumMap.hs
@@ -8,6 +8,7 @@
 -- Module      :  $Header$
 -- Description :  Data.IntMap with Enum keys.
 -- Copyright   :  (c) 2011-2019 Michal Terepeta
+--                (c) 2019-2020 Mikolaj Konarski and others (see git history)
 -- License     :  BSD3
 -- Maintainer  :  mikolaj.konarski@funktory.com
 -- Stability   :  alpha
diff --git a/Data/EnumMap/Base.hs b/Data/EnumMap/Base.hs
--- a/Data/EnumMap/Base.hs
+++ b/Data/EnumMap/Base.hs
@@ -7,6 +7,7 @@
 -- Module      :  $Header$
 -- Description :  Data.IntMap with Enum keys.
 -- Copyright   :  (c) 2011-2019 Michal Terepeta
+--                (c) 2019-2020 Mikolaj Konarski and others (see git history)
 -- License     :  BSD3
 -- Maintainer  :  mikolaj.konarski@funktory.com
 -- Stability   :  alpha
diff --git a/Data/EnumMap/Lazy.hs b/Data/EnumMap/Lazy.hs
--- a/Data/EnumMap/Lazy.hs
+++ b/Data/EnumMap/Lazy.hs
@@ -3,6 +3,7 @@
 -- Module      :  $Header$
 -- Description :  Data.IntMap.Lazy with Enum keys.
 -- Copyright   :  (c) 2011-2019 Michal Terepeta
+--                (c) 2019-2020 Mikolaj Konarski and others (see git history)
 -- License     :  BSD3
 -- Maintainer  :  mikolaj.konarski@funktory.com
 -- Stability   :  alpha
diff --git a/Data/EnumMap/Strict.hs b/Data/EnumMap/Strict.hs
--- a/Data/EnumMap/Strict.hs
+++ b/Data/EnumMap/Strict.hs
@@ -3,6 +3,7 @@
 -- Module      :  $Header$
 -- Description :  Data.IntMap.Strict with Enum keys.
 -- Copyright   :  (c) 2011-2019 Michal Terepeta
+--                (c) 2019-2020 Mikolaj Konarski and others (see git history)
 -- License     :  BSD3
 -- Maintainer  :  mikolaj.konarski@funktory.com
 -- Stability   :  alpha
diff --git a/Data/EnumSet.hs b/Data/EnumSet.hs
--- a/Data/EnumSet.hs
+++ b/Data/EnumSet.hs
@@ -5,6 +5,7 @@
 -- Module      :  $Header$
 -- Description :  Data.IntSet with Enum elements.
 -- Copyright   :  (c) 2011-2019 Michal Terepeta
+--                (c) 2019-2020 Mikolaj Konarski and others (see git history)
 -- License     :  BSD3
 -- Maintainer  :  mikolaj.konarski@funktory.com
 -- Stability   :  alpha
diff --git a/README.md b/README.md
--- a/README.md
+++ b/README.md
@@ -11,6 +11,6 @@
 Copyright
 ---------
 
-Copyright (c) 2011-2019 Michal Terepeta
+Copyright (c) 2011-2019 Michal Terepeta 
 
-Copyright (c) 2019 Mikolaj Konarski and others (see git history)
+Copyright (c) 2019-2020 Mikolaj Konarski and others (see git history)
diff --git a/enummapset.cabal b/enummapset.cabal
--- a/enummapset.cabal
+++ b/enummapset.cabal
@@ -1,5 +1,5 @@
 name:           enummapset
-version:        0.6.0.2
+version:        0.6.0.3
 synopsis:       IntMap and IntSet with Enum keys/elements.
 description:    This package contains simple wrappers around 'Data.IntMap' and
                 'Data.IntSet' with 'Enum' keys and elements respectively.
@@ -8,14 +8,13 @@
 bug-reports:    https://github.com/Mikolaj/enummapset/issues
 license:        BSD3
 license-file:   LICENSE
-tested-with:    GHC==7.8.4, GHC==7.10.3, GHC==8.0.2, GHC==8.2.2, GHC==8.4.4,
-                GHC==8.6.3
+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==8.8.3, GHC==8.10.1
 author:         Michal Terepeta
 maintainer:     Mikolaj Konarski <mikolaj.konarski@funktory.com>
 category:       Data Structures
 build-type:     Simple
 
-cabal-version:  >=1.8
+cabal-version:  >=1.10
 
 extra-source-files: README.md
 
@@ -46,6 +45,8 @@
   if flag(debug)
     ghc-options: -Wall
 
+  default-language: Haskell2010
+
   other-extensions: CPP, BangPatterns,
                     DataKinds, FlexibleContexts, FlexibleInstances,
                     KindSignatures, TypeFamilies, UndecidableInstances
@@ -61,6 +62,7 @@
 
   build-depends: base >= 4.6 && < 5, array >= 0.4.0.0, deepseq >= 1.2 && < 1.5, ghc-prim
   ghc-options: -O2
+  default-language: Haskell2010
   other-extensions: CPP, BangPatterns,
                     DataKinds, FlexibleContexts, FlexibleInstances,
                     KindSignatures, TypeFamilies, UndecidableInstances