diff --git a/.github/workflows/haskell-ci.yml b/.github/workflows/haskell-ci.yml
index ac1ee3df..382bff69 100644
--- a/.github/workflows/haskell-ci.yml
+++ b/.github/workflows/haskell-ci.yml
@@ -152,6 +152,8 @@ jobs:
             location: https://github.com/xmonad/xmonad
             branch:   master
 
+          optimization: False
+
           package xmonad-contrib
             flags:       +pedantic
             ghc-options: -j
diff --git a/cabal.haskell-ci b/cabal.haskell-ci
index 33a0dd13..77cb4c87 100644
--- a/cabal.haskell-ci
+++ b/cabal.haskell-ci
@@ -10,6 +10,7 @@ hlint: True
 hlint-yaml: .hlint.yaml
 
 raw-project
+  optimization: False
   package xmonad-contrib
     flags: +pedantic
     ghc-options: -j