diff --git a/CHANGELOG.md b/CHANGELOG.md
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -10,3 +10,6 @@
 - new Holiday data type
 - use "holidayKey" for a textual description
 - new countries supported: MOZ
+
+## **0.3.0.0** - 2025-08-20
+- default language is Haskell2010
diff --git a/holidays.cabal b/holidays.cabal
--- a/holidays.cabal
+++ b/holidays.cabal
@@ -1,7 +1,7 @@
-cabal-version: 3.8
+cabal-version: 3.0
 
 name: holidays
-version: 0.2.0.0
+version: 0.3.0.0
 synopsis: Library for country public holidays
 description:
   Library for country public holidays. Provides a small EDSL to describe holidays for a country.
@@ -13,7 +13,7 @@
 maintainer: danielc777888@gmail.com
 extra-doc-files: CHANGELOG.md
 
-tested-with: GHC == 9.4.8
+tested-with: GHC == 9.8.1 
 
 source-repository head
   type: git
@@ -22,11 +22,11 @@
 common common
   ghc-options: -Wall
   build-depends:
-    base ^>=4.17.2.1,
+    base ^>=4.19.0.0,
     containers ^>=0.7,
     text ^>=2.1,
     time >=1.4 && <2
-  default-language: GHC2021
+  default-language: Haskell2010 
 
 library
   import: common
diff --git a/src/Holidays.hs b/src/Holidays.hs
--- a/src/Holidays.hs
+++ b/src/Holidays.hs
@@ -12,16 +12,16 @@
 )
 where
 
-import Data.Set qualified as S
+import qualified Data.Set as S
 import Data.Time
 import Holidays.Base
 import Holidays.DateTransform
-import Holidays.Germany qualified as DEU
-import Holidays.Mozambique qualified as MOZ
-import Holidays.Namibia qualified as NAM
-import Holidays.SouthAfrica qualified as ZAF
-import Holidays.UnitedKingdom qualified as GBR
-import Holidays.UnitedStates qualified as USA
+import qualified Holidays.Germany as DEU
+import qualified Holidays.Mozambique as MOZ
+import qualified Holidays.Namibia as NAM
+import qualified Holidays.SouthAfrica as ZAF
+import qualified Holidays.UnitedKingdom as GBR
+import qualified Holidays.UnitedStates as USA
 
 {- |
 Returns a set of public holidays based on the country code (ISO_3166_1_Alpha_3) and a specific year.
@@ -51,3 +51,4 @@
 apply (hs, transforms) year =
   let validDays = filter (validDay . holidayValue) $ map (\d -> d year) hs -- apply year and filter out invalid days
   in  foldr (\d ds -> S.insert (foldr (\t d' -> t ds d') d transforms) ds) S.empty validDays -- apply transforms to valid days
+
diff --git a/src/Holidays/Base.hs b/src/Holidays/Base.hs
--- a/src/Holidays/Base.hs
+++ b/src/Holidays/Base.hs
@@ -8,7 +8,7 @@
   validDay,
 ) where
 
-import Data.Text qualified as T
+import qualified Data.Text as T
 import Data.Time
 
 -- | 3-letter country codes.
@@ -39,3 +39,4 @@
 -- | Day is valid if its not a nullDate
 validDay :: Day -> Bool
 validDay = not . (nullDay ==)
+
diff --git a/src/Holidays/DateFinder.hs b/src/Holidays/DateFinder.hs
--- a/src/Holidays/DateFinder.hs
+++ b/src/Holidays/DateFinder.hs
@@ -34,7 +34,7 @@
 ) where
 
 import Data.Maybe
-import Data.Set qualified as S
+import qualified Data.Set as S
 import Data.Time
 
 import Data.Time.Calendar.Easter
@@ -165,3 +165,4 @@
   | otherwise = d
   where
     d' = holidayValue d
+
diff --git a/src/Holidays/DateTransform.hs b/src/Holidays/DateTransform.hs
--- a/src/Holidays/DateTransform.hs
+++ b/src/Holidays/DateTransform.hs
@@ -4,7 +4,7 @@
   DateTransform,
 ) where
 
-import Data.Set qualified as S
+import qualified Data.Set as S
 import Data.Time
 import Holidays.Base
 import Holidays.DateFinder
diff --git a/tst/Main.hs b/tst/Main.hs
--- a/tst/Main.hs
+++ b/tst/Main.hs
@@ -1,11 +1,11 @@
 module Main where
 
-import Test.Holidays.Germany qualified as DEU
-import Test.Holidays.Mozambique qualified as MOZ
-import Test.Holidays.Namibia qualified as NAM
-import Test.Holidays.SouthAfrica qualified as ZAF
-import Test.Holidays.UnitedKingdom qualified as GBR
-import Test.Holidays.UnitedStates qualified as USA
+import qualified Test.Holidays.Germany as DEU
+import qualified Test.Holidays.Mozambique as MOZ
+import qualified Test.Holidays.Namibia as NAM
+import qualified Test.Holidays.SouthAfrica as ZAF
+import qualified Test.Holidays.UnitedKingdom as GBR
+import qualified Test.Holidays.UnitedStates as USA
 import Test.Tasty
 
 main :: IO ()
@@ -19,3 +19,4 @@
 
 propTests :: TestTree
 propTests = testGroup "Holidays property based tests" [DEU.propTests, GBR.propTests, MOZ.propTests, NAM.propTests, USA.propTests, ZAF.propTests]
+
diff --git a/tst/Test/Holidays.hs b/tst/Test/Holidays.hs
--- a/tst/Test/Holidays.hs
+++ b/tst/Test/Holidays.hs
@@ -3,9 +3,9 @@
   day,
 ) where
 
-import Data.Set qualified as S
+import qualified Data.Set as S
 import Data.Time
-import Holidays qualified as H
+import qualified Holidays as H
 import Test.Tasty
 import Test.Tasty.QuickCheck as QC
 
diff --git a/tst/Test/Holidays/Germany.hs b/tst/Test/Holidays/Germany.hs
--- a/tst/Test/Holidays/Germany.hs
+++ b/tst/Test/Holidays/Germany.hs
@@ -6,7 +6,7 @@
 ) where
 
 import Data.List
-import Data.Set qualified as S
+import qualified Data.Set as S
 import Holidays
 import Test.Holidays
 import Test.Tasty
@@ -47,3 +47,4 @@
 
 propTests :: TestTree
 propTests = countryPropTests "DEU" regions
+
diff --git a/tst/Test/Holidays/Mozambique.hs b/tst/Test/Holidays/Mozambique.hs
--- a/tst/Test/Holidays/Mozambique.hs
+++ b/tst/Test/Holidays/Mozambique.hs
@@ -6,7 +6,7 @@
 ) where
 
 import Data.List
-import Data.Set qualified as S
+import qualified Data.Set as S
 import Holidays
 import Test.Holidays
 import Test.Tasty
@@ -43,3 +43,4 @@
       hday "armed_forces_day" . sep 25,
       hday "day_of_peace_and_reconciliation" . oct 4,
       hday "family_day" . christmasDay -}
+
diff --git a/tst/Test/Holidays/Namibia.hs b/tst/Test/Holidays/Namibia.hs
--- a/tst/Test/Holidays/Namibia.hs
+++ b/tst/Test/Holidays/Namibia.hs
@@ -6,7 +6,7 @@
 ) where
 
 import Data.List
-import Data.Set qualified as S
+import qualified Data.Set as S
 import Holidays
 import Test.Holidays
 import Test.Tasty
@@ -51,3 +51,4 @@
 
 propTests :: TestTree
 propTests = countryPropTests "NAM" []
+
diff --git a/tst/Test/Holidays/SouthAfrica.hs b/tst/Test/Holidays/SouthAfrica.hs
--- a/tst/Test/Holidays/SouthAfrica.hs
+++ b/tst/Test/Holidays/SouthAfrica.hs
@@ -6,7 +6,7 @@
 ) where
 
 import Data.List
-import Data.Set qualified as S
+import qualified Data.Set as S
 import Holidays
 import Test.Holidays
 import Test.Tasty
@@ -51,3 +51,4 @@
 
 propTests :: TestTree
 propTests = countryPropTests "ZAF" []
+
diff --git a/tst/Test/Holidays/UnitedKingdom.hs b/tst/Test/Holidays/UnitedKingdom.hs
--- a/tst/Test/Holidays/UnitedKingdom.hs
+++ b/tst/Test/Holidays/UnitedKingdom.hs
@@ -6,7 +6,7 @@
 ) where
 
 import Data.List
-import Data.Set qualified as S
+import qualified Data.Set as S
 import Holidays
 import Test.Holidays
 import Test.Tasty
@@ -42,3 +42,4 @@
 
 propTests :: TestTree
 propTests = countryPropTests "GBR" []
+
diff --git a/tst/Test/Holidays/UnitedStates.hs b/tst/Test/Holidays/UnitedStates.hs
--- a/tst/Test/Holidays/UnitedStates.hs
+++ b/tst/Test/Holidays/UnitedStates.hs
@@ -6,7 +6,7 @@
 ) where
 
 import Data.List
-import Data.Set qualified as S
+import qualified Data.Set as S
 import Holidays
 import Test.Holidays
 import Test.Tasty
@@ -34,3 +34,4 @@
 
 propTests :: TestTree
 propTests = countryPropTests "USA" []
+