diff --git a/pkgs/top-level/haskell-defaults.nix b/pkgs/top-level/haskell-defaults.nix
index 37f6d580d304..7db61f4f63e2 100644
--- a/pkgs/top-level/haskell-defaults.nix
+++ b/pkgs/top-level/haskell-defaults.nix
@@ -20,7 +20,6 @@
   ghc741Prefs =
     self : self.haskellPlatformArgs_2012_2_0_0 self // {
       haskellPlatform = self.haskellPlatform_2012_2_0_0;
-      mtl1 = self.mtl_1_1_1_1; # 7.2 ok, 7.3 ok
       binary = null; # now a core package
     };
 
@@ -31,7 +30,6 @@
   ghc704Prefs =
     self : self.haskellPlatformArgs_2011_4_0_0 self // {
       haskellPlatform = self.haskellPlatform_2011_4_0_0;
-      mtl1 = self.mtl_1_1_1_1;
       repaExamples = null;      # don't pick this version of 'repa-examples' during nix-env -u
       cabalInstall_0_14_0 = self.cabalInstall_0_14_0.override { Cabal = self.Cabal_1_14_0; };
       monadPar = self.monadPar_0_1_0_3;
@@ -40,7 +38,6 @@
   ghc703Prefs =
     self : self.haskellPlatformArgs_2011_2_0_1 self // {
       haskellPlatform = self.haskellPlatform_2011_2_0_1;
-      mtl1 = self.mtl_1_1_1_1;
       repaExamples = null;      # don't pick this version of 'repa-examples' during nix-env -u
       cabalInstall_0_14_0 = self.cabalInstall_0_14_0.override { Cabal = self.Cabal_1_14_0; zlib = self.zlib_0_5_3_3; };
       monadPar = self.monadPar_0_1_0_3;
@@ -51,7 +48,6 @@
   ghc701Prefs =
     self : self.haskellPlatformArgs_2011_2_0_0 self // {
       haskellPlatform = self.haskellPlatform_2011_2_0_0;
-      mtl1 = self.mtl_1_1_1_1;
       repaExamples = null;      # don't pick this version of 'repa-examples' during nix-env -u
       cabalInstall_0_14_0 = self.cabalInstall_0_14_0.override { Cabal = self.Cabal_1_14_0; zlib = self.zlib_0_5_3_3; };
       monadPar = self.monadPar_0_1_0_3;
@@ -62,6 +58,7 @@
   ghc6122Prefs =
     self : self.haskellPlatformArgs_2010_2_0_0 self // {
       haskellPlatform = self.haskellPlatform_2010_2_0_0;
+      mtl1 = self.mtl_1_1_0_2;
       repaExamples = null;      # don't pick this version of 'repa-examples' during nix-env -u
       cabalInstall_0_14_0 = self.cabalInstall_0_14_0.override { Cabal = self.Cabal_1_14_0; zlib = self.zlib_0_5_3_3; };
       monadPar = self.monadPar_0_1_0_3;
@@ -72,6 +69,7 @@
   ghc6121Prefs =
     self : self.haskellPlatformArgs_2010_1_0_0 self // {
       haskellPlatform = self.haskellPlatform_2010_1_0_0;
+      mtl1 = self.mtl_1_1_0_2;
       extensibleExceptions = self.extensibleExceptions_0_1_1_0;
       repaExamples = null;      # don't pick this version of 'repa-examples' during nix-env -u
       deepseq = self.deepseq_1_1_0_2;
@@ -82,6 +80,7 @@
   ghc6104Prefs =
     self : self.haskellPlatformArgs_2009_2_0_2 self // {
       haskellPlatform = self.haskellPlatform_2009_2_0_2;
+      mtl1 = self.mtl_1_1_0_2;
       extensibleExceptions = self.extensibleExceptions_0_1_1_0;
       text = self.text_0_11_0_6;
       repaExamples = null;      # don't pick this version of 'repa-examples' during nix-env -u
diff --git a/pkgs/top-level/haskell-packages.nix b/pkgs/top-level/haskell-packages.nix
index aa484c0a30a7..cd42de321c21 100644
--- a/pkgs/top-level/haskell-packages.nix
+++ b/pkgs/top-level/haskell-packages.nix
@@ -1029,7 +1029,7 @@ let result = let callPackage = x : y : modifyPrio (newScope result.final x y);
   mtl_2_1_1 = callPackage ../development/libraries/haskell/mtl/2.1.1.nix {
     transformers = self.transformers_0_3_0_0;
   };
-  mtl1 = self.mtl_1_1_0_2;
+  mtl1 = self.mtl_1_1_1_1;
   mtl2 = self.mtl_2_1_1;
   mtl  = self.mtl2;