diff --git a/containers-tests/benchmarks/IntSet.hs b/containers-tests/benchmarks/IntSet.hs
index 1772b68de..119a5feeb 100644
--- a/containers-tests/benchmarks/IntSet.hs
+++ b/containers-tests/benchmarks/IntSet.hs
@@ -1,4 +1,3 @@
-{-# LANGUAGE CPP #-}
 {-# LANGUAGE BangPatterns, GeneralizedNewtypeDeriving #-}
 
 module Main where
diff --git a/containers-tests/tests/bitqueue-properties.hs b/containers-tests/tests/bitqueue-properties.hs
index 95ce473a3..6558b7016 100644
--- a/containers-tests/tests/bitqueue-properties.hs
+++ b/containers-tests/tests/bitqueue-properties.hs
@@ -1,4 +1,3 @@
-{-# LANGUAGE CPP #-}
 {-# LANGUAGE BangPatterns #-}
 
 import qualified Data.List as List
diff --git a/containers-tests/tests/intset-properties.hs b/containers-tests/tests/intset-properties.hs
index bac0039bf..123fb90ff 100644
--- a/containers-tests/tests/intset-properties.hs
+++ b/containers-tests/tests/intset-properties.hs
@@ -1,4 +1,3 @@
-{-# LANGUAGE CPP #-}
 import Control.Applicative (Const(..))
 import Data.Bits ((.&.), popCount)
 import Data.Coerce (coerce)
diff --git a/containers-tests/tests/seq-properties.hs b/containers-tests/tests/seq-properties.hs
index eb7d0aa6f..50557f0d4 100644
--- a/containers-tests/tests/seq-properties.hs
+++ b/containers-tests/tests/seq-properties.hs
@@ -1,9 +1,6 @@
 {-# LANGUAGE CPP #-}
-{-# LANGUAGE PatternGuards #-}
 {-# LANGUAGE TemplateHaskell #-}
 
-#include "containers.h"
-
 import Data.Sequence.Internal
   ( Sized (..)
   , Seq (Seq)
diff --git a/containers-tests/tests/set-properties.hs b/containers-tests/tests/set-properties.hs
index 63c1e9da5..42fc7fbf4 100644
--- a/containers-tests/tests/set-properties.hs
+++ b/containers-tests/tests/set-properties.hs
@@ -1,4 +1,3 @@
-{-# LANGUAGE CPP #-}
 {-# LANGUAGE GeneralizedNewtypeDeriving #-}
 import qualified Data.IntSet as IntSet
 import Data.Coerce (coerce)
diff --git a/containers/src/Data/IntMap.hs b/containers/src/Data/IntMap.hs
index 32b93dcfb..2fba64a57 100644
--- a/containers/src/Data/IntMap.hs
+++ b/containers/src/Data/IntMap.hs
@@ -3,8 +3,6 @@
 {-# LANGUAGE Safe #-}
 #endif
 
-#include "containers.h"
-
 -----------------------------------------------------------------------------
 -- |
 -- Module      :  Data.IntMap
diff --git a/containers/src/Data/IntMap/Internal.hs b/containers/src/Data/IntMap/Internal.hs
index bfd1be25e..ac838f289 100644
--- a/containers/src/Data/IntMap/Internal.hs
+++ b/containers/src/Data/IntMap/Internal.hs
@@ -1,10 +1,7 @@
 {-# LANGUAGE CPP #-}
 {-# LANGUAGE BangPatterns #-}
-{-# LANGUAGE PatternGuards #-}
 #ifdef __GLASGOW_HASKELL__
 {-# LANGUAGE DeriveLift #-}
-{-# LANGUAGE MagicHash #-}
-{-# LANGUAGE ScopedTypeVariables #-}
 {-# LANGUAGE StandaloneDeriving #-}
 {-# LANGUAGE TypeFamilies #-}
 {-# LANGUAGE Trustworthy #-}
@@ -12,8 +9,6 @@
 
 {-# OPTIONS_HADDOCK not-home #-}
 
-#include "containers.h"
-
 -----------------------------------------------------------------------------
 -- |
 -- Module      :  Data.IntMap.Internal
diff --git a/containers/src/Data/IntMap/Lazy.hs b/containers/src/Data/IntMap/Lazy.hs
index dc59151b9..1ef3aee11 100644
--- a/containers/src/Data/IntMap/Lazy.hs
+++ b/containers/src/Data/IntMap/Lazy.hs
@@ -3,8 +3,6 @@
 {-# LANGUAGE Safe #-}
 #endif
 
-#include "containers.h"
-
 -----------------------------------------------------------------------------
 -- |
 -- Module      :  Data.IntMap.Lazy
diff --git a/containers/src/Data/IntMap/Merge/Lazy.hs b/containers/src/Data/IntMap/Merge/Lazy.hs
index 5ff13fe05..1d903898b 100644
--- a/containers/src/Data/IntMap/Merge/Lazy.hs
+++ b/containers/src/Data/IntMap/Merge/Lazy.hs
@@ -3,8 +3,6 @@
 {-# LANGUAGE Safe #-}
 #endif
 
-#include "containers.h"
-
 -----------------------------------------------------------------------------
 -- |
 -- Module      :  Data.IntMap.Merge.Lazy
diff --git a/containers/src/Data/IntMap/Merge/Strict.hs b/containers/src/Data/IntMap/Merge/Strict.hs
index e17770959..2819f940c 100644
--- a/containers/src/Data/IntMap/Merge/Strict.hs
+++ b/containers/src/Data/IntMap/Merge/Strict.hs
@@ -4,8 +4,6 @@
 {-# LANGUAGE Trustworthy #-}
 #endif
 
-#include "containers.h"
-
 -----------------------------------------------------------------------------
 -- |
 -- Module      :  Data.IntMap.Merge.Strict
diff --git a/containers/src/Data/IntMap/Strict.hs b/containers/src/Data/IntMap/Strict.hs
index 80ccad590..15f0d1d36 100644
--- a/containers/src/Data/IntMap/Strict.hs
+++ b/containers/src/Data/IntMap/Strict.hs
@@ -3,8 +3,6 @@
 {-# LANGUAGE Trustworthy #-}
 #endif
 
-#include "containers.h"
-
 -----------------------------------------------------------------------------
 -- |
 -- Module      :  Data.IntMap.Strict
diff --git a/containers/src/Data/IntMap/Strict/Internal.hs b/containers/src/Data/IntMap/Strict/Internal.hs
index 0bce5c9bc..4977a0676 100644
--- a/containers/src/Data/IntMap/Strict/Internal.hs
+++ b/containers/src/Data/IntMap/Strict/Internal.hs
@@ -1,8 +1,5 @@
 {-# LANGUAGE CPP #-}
 {-# LANGUAGE BangPatterns #-}
-{-# LANGUAGE PatternGuards #-}
-
-#include "containers.h"
 
 -----------------------------------------------------------------------------
 -- |
diff --git a/containers/src/Data/IntSet.hs b/containers/src/Data/IntSet.hs
index 46291efb5..630d58b1f 100644
--- a/containers/src/Data/IntSet.hs
+++ b/containers/src/Data/IntSet.hs
@@ -3,8 +3,6 @@
 {-# LANGUAGE Safe #-}
 #endif
 
-#include "containers.h"
-
 -----------------------------------------------------------------------------
 -- |
 -- Module      :  Data.IntSet
diff --git a/containers/src/Data/IntSet/Internal.hs b/containers/src/Data/IntSet/Internal.hs
index fa7355914..8efde8137 100644
--- a/containers/src/Data/IntSet/Internal.hs
+++ b/containers/src/Data/IntSet/Internal.hs
@@ -1,9 +1,7 @@
 {-# LANGUAGE CPP #-}
 {-# LANGUAGE BangPatterns #-}
-{-# LANGUAGE PatternGuards #-}
 #ifdef __GLASGOW_HASKELL__
 {-# LANGUAGE DeriveLift #-}
-{-# LANGUAGE MagicHash #-}
 {-# LANGUAGE StandaloneDeriving #-}
 {-# LANGUAGE TypeFamilies #-}
 {-# LANGUAGE Trustworthy #-}
diff --git a/containers/src/Data/Map.hs b/containers/src/Data/Map.hs
index be0f1107d..c80aebb06 100644
--- a/containers/src/Data/Map.hs
+++ b/containers/src/Data/Map.hs
@@ -3,8 +3,6 @@
 {-# LANGUAGE Safe #-}
 #endif
 
-#include "containers.h"
-
 -----------------------------------------------------------------------------
 -- |
 -- Module      :  Data.Map
diff --git a/containers/src/Data/Map/Internal.hs b/containers/src/Data/Map/Internal.hs
index b3bcd056c..53dc6780c 100644
--- a/containers/src/Data/Map/Internal.hs
+++ b/containers/src/Data/Map/Internal.hs
@@ -1,6 +1,5 @@
 {-# LANGUAGE CPP #-}
 {-# LANGUAGE BangPatterns #-}
-{-# LANGUAGE PatternGuards #-}
 #if defined(__GLASGOW_HASKELL__)
 {-# LANGUAGE DeriveLift #-}
 {-# LANGUAGE RoleAnnotations #-}
diff --git a/containers/src/Data/Map/Internal/Debug.hs b/containers/src/Data/Map/Internal/Debug.hs
index a0fb332ec..e42eeffbf 100644
--- a/containers/src/Data/Map/Internal/Debug.hs
+++ b/containers/src/Data/Map/Internal/Debug.hs
@@ -1,6 +1,3 @@
-{-# LANGUAGE CPP #-}
-#include "containers.h"
-
 module Data.Map.Internal.Debug where
 
 import Data.Map.Internal (Map (..), size, delta)
diff --git a/containers/src/Data/Map/Lazy.hs b/containers/src/Data/Map/Lazy.hs
index c5d40c76c..553e28f62 100644
--- a/containers/src/Data/Map/Lazy.hs
+++ b/containers/src/Data/Map/Lazy.hs
@@ -3,8 +3,6 @@
 {-# LANGUAGE Safe #-}
 #endif
 
-#include "containers.h"
-
 -----------------------------------------------------------------------------
 -- |
 -- Module      :  Data.Map.Lazy
diff --git a/containers/src/Data/Map/Merge/Lazy.hs b/containers/src/Data/Map/Merge/Lazy.hs
index 5ac059ab9..c23a4f03c 100644
--- a/containers/src/Data/Map/Merge/Lazy.hs
+++ b/containers/src/Data/Map/Merge/Lazy.hs
@@ -3,8 +3,6 @@
 {-# LANGUAGE Safe #-}
 #endif
 
-#include "containers.h"
-
 -----------------------------------------------------------------------------
 -- |
 -- Module      :  Data.Map.Merge.Lazy
diff --git a/containers/src/Data/Map/Merge/Strict.hs b/containers/src/Data/Map/Merge/Strict.hs
index 1cc8954a9..d4181bbbe 100644
--- a/containers/src/Data/Map/Merge/Strict.hs
+++ b/containers/src/Data/Map/Merge/Strict.hs
@@ -3,8 +3,6 @@
 {-# LANGUAGE Safe #-}
 #endif
 
-#include "containers.h"
-
 -----------------------------------------------------------------------------
 -- |
 -- Module      :  Data.Map.Merge.Strict
diff --git a/containers/src/Data/Map/Strict.hs b/containers/src/Data/Map/Strict.hs
index 75757d937..4722c088b 100644
--- a/containers/src/Data/Map/Strict.hs
+++ b/containers/src/Data/Map/Strict.hs
@@ -3,8 +3,6 @@
 {-# LANGUAGE Safe #-}
 #endif
 
-#include "containers.h"
-
 -----------------------------------------------------------------------------
 -- |
 -- Module      :  Data.Map.Strict
diff --git a/containers/src/Data/Map/Strict/Internal.hs b/containers/src/Data/Map/Strict/Internal.hs
index 7275b9bf8..aad8354ce 100644
--- a/containers/src/Data/Map/Strict/Internal.hs
+++ b/containers/src/Data/Map/Strict/Internal.hs
@@ -5,8 +5,6 @@
 #endif
 {-# OPTIONS_HADDOCK not-home #-}
 
-#include "containers.h"
-
 -----------------------------------------------------------------------------
 -- |
 -- Module      :  Data.Map.Strict.Internal
diff --git a/containers/src/Data/Sequence/Internal.hs b/containers/src/Data/Sequence/Internal.hs
index 4b6bfa09d..38804a039 100644
--- a/containers/src/Data/Sequence/Internal.hs
+++ b/containers/src/Data/Sequence/Internal.hs
@@ -6,7 +6,6 @@
 {-# LANGUAGE DeriveGeneric #-}
 {-# LANGUAGE DeriveLift #-}
 {-# LANGUAGE StandaloneDeriving #-}
-{-# LANGUAGE FlexibleInstances #-}
 {-# LANGUAGE InstanceSigs #-}
 {-# LANGUAGE ScopedTypeVariables #-}
 {-# LANGUAGE TemplateHaskellQuotes #-}
@@ -18,7 +17,6 @@
 {-# LANGUAGE PatternSynonyms #-}
 {-# LANGUAGE ViewPatterns #-}
 #endif
-{-# LANGUAGE PatternGuards #-}
 
 {-# OPTIONS_HADDOCK not-home #-}
 
diff --git a/containers/src/Data/Set.hs b/containers/src/Data/Set.hs
index d33ff4eb4..c3e805410 100644
--- a/containers/src/Data/Set.hs
+++ b/containers/src/Data/Set.hs
@@ -3,8 +3,6 @@
 {-# LANGUAGE Safe #-}
 #endif
 
-#include "containers.h"
-
 -----------------------------------------------------------------------------
 -- |
 -- Module      :  Data.Set
diff --git a/containers/src/Data/Set/Internal.hs b/containers/src/Data/Set/Internal.hs
index 780caf5b7..4800516e5 100644
--- a/containers/src/Data/Set/Internal.hs
+++ b/containers/src/Data/Set/Internal.hs
@@ -1,6 +1,5 @@
 {-# LANGUAGE CPP #-}
 {-# LANGUAGE BangPatterns #-}
-{-# LANGUAGE PatternGuards #-}
 #ifdef __GLASGOW_HASKELL__
 {-# LANGUAGE Trustworthy #-}
 {-# LANGUAGE DeriveLift #-}
@@ -11,8 +10,6 @@
 
 {-# OPTIONS_HADDOCK not-home #-}
 
-#include "containers.h"
-
 -----------------------------------------------------------------------------
 -- |
 -- Module      :  Data.Set.Internal
diff --git a/containers/src/Data/Tree.hs b/containers/src/Data/Tree.hs
index f7e838553..c9c2bb5a4 100644
--- a/containers/src/Data/Tree.hs
+++ b/containers/src/Data/Tree.hs
@@ -1,5 +1,4 @@
 {-# LANGUAGE BangPatterns #-}
-{-# LANGUAGE PatternGuards #-}
 {-# LANGUAGE CPP #-}
 #if __GLASGOW_HASKELL__
 {-# LANGUAGE DeriveDataTypeable #-}
@@ -8,8 +7,6 @@
 {-# LANGUAGE Trustworthy #-}
 #endif
 
-#include "containers.h"
-
 -----------------------------------------------------------------------------
 -- |
 -- Module      :  Data.Tree
diff --git a/containers/src/Utils/Containers/Internal/BitQueue.hs b/containers/src/Utils/Containers/Internal/BitQueue.hs
index 43781a50e..f7618c8d2 100644
--- a/containers/src/Utils/Containers/Internal/BitQueue.hs
+++ b/containers/src/Utils/Containers/Internal/BitQueue.hs
@@ -1,8 +1,5 @@
-{-# LANGUAGE CPP #-}
 {-# LANGUAGE BangPatterns #-}
 
-#include "containers.h"
-
 -----------------------------------------------------------------------------
 -- |
 -- Module      :  Utils.Containers.Internal.BitQueue
diff --git a/containers/src/Utils/Containers/Internal/BitUtil.hs b/containers/src/Utils/Containers/Internal/BitUtil.hs
index e82d29e5b..0d2c3e4ed 100644
--- a/containers/src/Utils/Containers/Internal/BitUtil.hs
+++ b/containers/src/Utils/Containers/Internal/BitUtil.hs
@@ -1,11 +1,8 @@
 {-# LANGUAGE CPP #-}
 #ifdef __GLASGOW_HASKELL__
 {-# LANGUAGE MagicHash #-}
-{-# LANGUAGE Trustworthy #-}
 #endif
 
-#include "containers.h"
-
 -----------------------------------------------------------------------------
 -- |
 -- Module      :  Utils.Containers.Internal.BitUtil
diff --git a/containers/src/Utils/Containers/Internal/State.hs b/containers/src/Utils/Containers/Internal/State.hs
index 96b898b38..e2c0b051e 100644
--- a/containers/src/Utils/Containers/Internal/State.hs
+++ b/containers/src/Utils/Containers/Internal/State.hs
@@ -1,5 +1,3 @@
-{-# LANGUAGE CPP #-}
-#include "containers.h"
 {-# OPTIONS_HADDOCK hide #-}
 
 -- | A clone of Control.Monad.State.Strict.