diff --git a/pkgs/development/haskell-modules/configuration-ghc-7.8.x.nix b/pkgs/development/haskell-modules/configuration-ghc-7.8.x.nix
index ab58d0123927..ebb12ed20a8c 100644
--- a/pkgs/development/haskell-modules/configuration-ghc-7.8.x.nix
+++ b/pkgs/development/haskell-modules/configuration-ghc-7.8.x.nix
@@ -75,6 +75,9 @@ self: super: {
   hosc = dontDistribute super.hosc;
   tidal-midi = dontDistribute super.tidal-midi;
 
+  # Needs mtl 2.2.x due to "plailude".
+  clac = dontDistribute super.clac;
+
 }
 
 // # packages relating to amazonka