diff --git a/pkgs/development/libraries/haskell/ltk/default.nix b/pkgs/development/libraries/haskell/ltk/default.nix
index a45169b4cc1..a945512fa1c 100644
--- a/pkgs/development/libraries/haskell/ltk/default.nix
+++ b/pkgs/development/libraries/haskell/ltk/default.nix
@@ -5,6 +5,9 @@ cabal.mkDerivation (self: {
   version = "0.12.0.0";
   sha256 = "1hlsfi77yypfnvh1alr3rflbffby9pbmc71m507davr6b09v9w9f";
   buildDepends = [ Cabal filepath glib gtk mtl parsec transformers ];
+  patchPhase = ''
+    sed -i -e 's|mtl >=1.1.0.2 && <2.1|mtl|' -e 's|transformers >=0.2.2.0 && <0.3|transformers|' ltk.cabal
+  '';
   meta = {
     homepage = "http://www.leksah.org";
     description = "Leksah tool kit";
diff --git a/pkgs/top-level/haskell-defaults.nix b/pkgs/top-level/haskell-defaults.nix
index 226fe64d91d..42f0980c637 100644
--- a/pkgs/top-level/haskell-defaults.nix
+++ b/pkgs/top-level/haskell-defaults.nix
@@ -26,9 +26,6 @@
 
   ghc741Prefs =
     self : ghc741Prefs_pedantic self // {
-      # These are necessary at the moment to prevent many packages from breaking.
-      mtl          = self.mtl_2_0_1_0;
-      transformers = self.transformers_0_2_2_0;
     };
 
   ghc722Prefs = ghc741Prefs;
@@ -266,5 +263,5 @@
                            ghc704Binary;
                prefFun = ghcHEADPrefs;
              };
-  
+
 }