diff --git a/.github/workflows/haskell-ci.yml b/.github/workflows/haskell-ci.yml
index 2715295..1b54726 100644
--- a/.github/workflows/haskell-ci.yml
+++ b/.github/workflows/haskell-ci.yml
@@ -66,11 +66,6 @@ jobs:
             compilerVersion: 8.6.5
             setup-method: hvr-ppa
             allow-failure: false
-          - compiler: ghc-8.4.4
-            compilerKind: ghc
-            compilerVersion: 8.4.4
-            setup-method: hvr-ppa
-            allow-failure: false
       fail-fast: false
     steps:
       - name: apt
diff --git a/.github/workflows/stack.yml b/.github/workflows/stack.yml
index e169cd4..36bdcd1 100644
--- a/.github/workflows/stack.yml
+++ b/.github/workflows/stack.yml
@@ -12,7 +12,6 @@ jobs:
       fail-fast: false
       matrix:
         include:
-          - resolver: lts-12  # GHC 8.4
           - resolver: lts-14  # GHC 8.6
           - resolver: lts-16  # GHC 8.8
           - resolver: lts-18  # GHC 8.10
diff --git a/CHANGES.md b/CHANGES.md
index 5da39ae..f26f2a6 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -4,6 +4,8 @@
 
 ### Breaking Changes
 
+* Dropped support for GHC 8.4.
+
 ### Enhancements
 
 * Exported `sendRestart` and `sendReplace` from `XMonad.Operations`.
diff --git a/stack.yaml b/stack.yaml
index 2ec4a08..99ffada 100644
--- a/stack.yaml
+++ b/stack.yaml
@@ -6,13 +6,6 @@ packages:
 extra-deps:
 - X11-1.10
 
-flags:
-  xmonad:
-    # stack doesn't support automatic flags
-    # https://cabal.readthedocs.io/en/latest/cabal-package.html#resolution-of-conditions-and-flags
-    # https://github.com/commercialhaskell/stack/issues/1313#issuecomment-157259270
-    quickcheck-classes: false
-
 nix:
   packages:
     - zlib
diff --git a/tests/Properties/Stack.hs b/tests/Properties/Stack.hs
index f85ca3e..a833ce1 100644
--- a/tests/Properties/Stack.hs
+++ b/tests/Properties/Stack.hs
@@ -1,9 +1,5 @@
-{-# LANGUAGE CPP #-}
 {-# LANGUAGE ScopedTypeVariables #-}
-
-#ifdef VERSION_quickcheck_classes
 {-# LANGUAGE GeneralizedNewtypeDeriving #-}
-#endif
 
 module Properties.Stack where
 
@@ -15,13 +11,11 @@ import qualified XMonad.StackSet as S (filter)
 
 import Data.Maybe
 
-#ifdef VERSION_quickcheck_classes
 import Data.Proxy
 import Test.QuickCheck.Classes (
     Laws (lawsTypeclass, lawsProperties), Proxy1 (Proxy1),
     foldableLaws, traversableLaws,
     )
-#endif
 
 
 -- The list returned by index should be the same length as the actual
@@ -65,7 +59,6 @@ prop_differentiate xs =
     where _ = xs :: [Int]
 
 
-#ifdef VERSION_quickcheck_classes
 -- Check type class laws of 'Data.Foldable.Foldable' and 'Data.Traversable.Traversable'.
 newtype TestStack a = TestStack (Stack a)
     deriving (Eq, Read, Show, Foldable, Functor)
@@ -82,6 +75,3 @@ prop_laws_Stack = format (foldableLaws p) <> format (traversableLaws p)
     p = Proxy :: Proxy TestStack
     format laws = [ ("Stack: " <> lawsTypeclass laws <> ": " <> name, prop)
                   | (name, prop) <- lawsProperties laws ]
-#else
-prop_laws_Stack = []
-#endif
diff --git a/xmonad.cabal b/xmonad.cabal
index da24c52..a26797b 100644
--- a/xmonad.cabal
+++ b/xmonad.cabal
@@ -27,7 +27,7 @@ author:             Spencer Janssen, Don Stewart, Adam Vogt, David Roundy, Jason
                     Ondřej Súkup, Paul Hebble, Shachaf Ben-Kiki, Siim Põder, Tim McIver,
                     Trevor Elliott, Wouter Swierstra, Conrad Irwin, Tim Thelion, Tony Zorman
 maintainer:         xmonad@haskell.org
-tested-with:        GHC == 8.4.4 || == 8.6.5 || == 8.8.4 || == 8.10.7 || == 9.0.2 || == 9.2.5 || == 9.4.2
+tested-with:        GHC == 8.6.5 || == 8.8.4 || == 8.10.7 || == 9.0.2 || == 9.2.5 || == 9.4.2
 category:           System
 homepage:           http://xmonad.org
 bug-reports:        https://github.com/xmonad/xmonad/issues
@@ -54,8 +54,6 @@ flag pedantic
   default:     False
   manual:      True
 
-flag quickcheck-classes
-
 library
   exposed-modules: XMonad
                    XMonad.Config
@@ -83,7 +81,7 @@ library
   default-language: Haskell2010
 
   -- Keep this in sync with the oldest version in 'tested-with'
-  if impl(ghc > 8.4.4)
+  if impl(ghc > 8.6.5)
     ghc-options:   -Wno-unused-imports
 
   if flag(pedantic)
@@ -96,7 +94,7 @@ executable xmonad
   default-language: Haskell2010
 
   -- Keep this in sync with the oldest version in 'tested-with'
-  if impl(ghc > 8.4.4)
+  if impl(ghc > 8.6.5)
     ghc-options:   -Wno-unused-imports
 
   if flag(pedantic)
@@ -125,15 +123,11 @@ test-suite properties
   hs-source-dirs: tests
   build-depends:  base
                 , QuickCheck >= 2
+                , quickcheck-classes >= 0.4.3
                 , X11
                 , containers
                 , xmonad
   default-language: Haskell2010
 
-  if flag(quickcheck-classes) && impl(ghc > 8.5)
-    -- no quickcheck-classes in LTS-12
-    -- GHC 8.4 and lower needs too much boilerplate (Eq1, Show1, …)
-    build-depends: quickcheck-classes >= 0.4.3
-
   if flag(pedantic)
     ghc-options:   -Werror