diff --git a/src/Algorithm.hs b/src/Algorithm.hs
index 4babc58aa496c7b20066f74a6af5587ae451bf4b..d25c8346b9991901a365774fcba6321800672972 100644
--- a/src/Algorithm.hs
+++ b/src/Algorithm.hs
@@ -1,12 +1,8 @@
-{-# LANGUAGE TupleSections #-}
 {-# LANGUAGE TypeApplications #-}
 {-# LANGUAGE UndecidableInstances #-}
 {-# LANGUAGE FlexibleContexts #-}
-{-# LANGUAGE StandaloneDeriving #-}
-{-# LANGUAGE GADTs #-}
 {-# LANGUAGE RecordWildCards #-}
 {-# LANGUAGE ScopedTypeVariables #-}
-{-# LANGUAGE LambdaCase #-}
 module Algorithm
   ( initializeAll
   , finalizeStates
diff --git a/src/Data/BlockQueue.hs b/src/Data/BlockQueue.hs
index c87e4a5b424a311d8af748029aff9a7b48b2f0a7..924b6913138a0bc1e2b494f6898bffffe0845639 100644
--- a/src/Data/BlockQueue.hs
+++ b/src/Data/BlockQueue.hs
@@ -1,6 +1,5 @@
 {-# LANGUAGE BangPatterns #-}
 {-# LANGUAGE TemplateHaskell #-}
-{-# LANGUAGE LambdaCase #-}
 {-# LANGUAGE StrictData #-}
 
 -- | A queue for sorted blocks that can be used in the lumping algorithm.
diff --git a/src/Data/Functors.hs b/src/Data/Functors.hs
index 3c2150b48a151fa250ef76014381e6ae6e88de6a..0632844a9a41063acc92d4177d61fcb2af11ea5b 100644
--- a/src/Data/Functors.hs
+++ b/src/Data/Functors.hs
@@ -1,4 +1,3 @@
-{-# LANGUAGE GADTs #-}
 {-# LANGUAGE PolyKinds #-}
 
 module Data.Functors
diff --git a/src/Data/MorphismEncoding.hs b/src/Data/MorphismEncoding.hs
index 4619e5b9ea6942b5cad8092e93c7fef7a67dad41..d11bb22e8d027d4a4e334a608affd2e694b31d02 100644
--- a/src/Data/MorphismEncoding.hs
+++ b/src/Data/MorphismEncoding.hs
@@ -1,4 +1,3 @@
-{-# LANGUAGE GADTs #-}
 {-# LANGUAGE RecordWildCards #-}
 module Data.MorphismEncoding
   ( Encoding(..)
diff --git a/src/Data/OpenUnion.hs b/src/Data/OpenUnion.hs
index 69b3e31c8ba8501d07b49e28d0eb9149bcc2a392..b9fd4f6cf4f4a89f91c8114fb1d2a79db905ca10 100644
--- a/src/Data/OpenUnion.hs
+++ b/src/Data/OpenUnion.hs
@@ -6,7 +6,6 @@
 {-# LANGUAGE MultiParamTypeClasses #-}
 {-# LANGUAGE KindSignatures #-}
 {-# LANGUAGE DataKinds #-}
-{-# LANGUAGE GADTs #-}
 {-# LANGUAGE ScopedTypeVariables #-}
 {-# OPTIONS_HADDOCK prune #-}
 
diff --git a/src/Data/RefinementInterface.hs b/src/Data/RefinementInterface.hs
index fd07c3d4fe797db459aebfaedd9bbddffc9d508f..6371e5e07a0f333e2b7970453b8dfc5798af4cf3 100644
--- a/src/Data/RefinementInterface.hs
+++ b/src/Data/RefinementInterface.hs
@@ -2,8 +2,6 @@
 {-# LANGUAGE FlexibleContexts #-}
 {-# LANGUAGE RankNTypes #-}
 {-# LANGUAGE Rank2Types #-}
-{-# LANGUAGE TypeFamilies #-}
-{-# LANGUAGE GADTs #-}
 {-# LANGUAGE PolyKinds #-}
 module Data.RefinementInterface where
 
diff --git a/src/Data/Sort.hs b/src/Data/Sort.hs
index d422d689636f9eb16315a8ac4b28a944c04d1331..c452246147092fdecc8ed79643dfd318e37145a0 100644
--- a/src/Data/Sort.hs
+++ b/src/Data/Sort.hs
@@ -1,4 +1,3 @@
-{-# LANGUAGE GADTs #-}
 {-# LANGUAGE DataKinds #-}
 module Data.Sort
   ( Sort
diff --git a/src/Parser.hs b/src/Parser.hs
index d8dd5094979ad4bf92c73a70a407c6e7b1cfdd20..2077ff5a1a5f429420b1ba999a2bf5f975d485e5 100644
--- a/src/Parser.hs
+++ b/src/Parser.hs
@@ -1,7 +1,5 @@
 {-# LANGUAGE ScopedTypeVariables #-}
 {-# LANGUAGE PolyKinds #-}
-{-# LANGUAGE GADTs #-}
-{-# LANGUAGE OverloadedStrings #-}
 
 module Parser (decodeCoalgebra) where
 
diff --git a/src/Text/Parser/Lexer.hs b/src/Text/Parser/Lexer.hs
index 5c0bbf23f98ed3c2419fe5bc8028ec8c3e353e09..03049231a2cd020a0813d5445c0780f31fa10dce 100644
--- a/src/Text/Parser/Lexer.hs
+++ b/src/Text/Parser/Lexer.hs
@@ -1,5 +1,3 @@
-{-# LANGUAGE OverloadedStrings #-}
-
 module Text.Parser.Lexer
   ( spaceConsumer
   , symbol
diff --git a/tests/Data/RefinablePartitionSpec.hs b/tests/Data/RefinablePartitionSpec.hs
index 488f2cc13891d24cba2344a5aa7213ca13fe5ac4..8dbdc0fb5f456f7485f109ce5b46f4e267270f12 100644
--- a/tests/Data/RefinablePartitionSpec.hs
+++ b/tests/Data/RefinablePartitionSpec.hs
@@ -1,5 +1,4 @@
 {-# LANGUAGE ScopedTypeVariables #-}
-{-# LANGUAGE TupleSections #-}
 
 module Data.RefinablePartitionSpec (spec) where
 
diff --git a/tests/DocTests.hs b/tests/DocTests.hs
index 1969cdbfdcbc7ad33ae8a6656bb7150d1be298d0..a150e022fbddb1927a1b24295805f991b0f6445c 100644
--- a/tests/DocTests.hs
+++ b/tests/DocTests.hs
@@ -1,4 +1,3 @@
-{-# LANGUAGE GADTs #-}
 module Main where
 
 import Build_doctests (flags, pkgs, module_sources)