diff --git a/pkgs/top-level/haskell-packages.nix b/pkgs/top-level/haskell-packages.nix
index 5b899ab51508..508bf6100651 100644
--- a/pkgs/top-level/haskell-packages.nix
+++ b/pkgs/top-level/haskell-packages.nix
@@ -157,8 +157,8 @@ let result = let callPackage = x : y : modifyPrio (newScope result.final x y);
     zlib         = self.zlib_0_5_3_3;           # 7.4.1 ok
     HTTP         = self.HTTP_4000_2_3;          # 7.4.1 ok
     text         = self.text_0_11_2_0;          # 7.4.1 ok
-    transformers = self.transformers_0_3_0_0;   # 7.4.1 ok
-    mtl          = self.mtl_2_1_1;              # 7.4.1 ok
+    transformers = self.transformers_0_2_2_0;   # 7.4.1 ok
+    mtl          = self.mtl_2_0_1_0;            # 7.4.1 ok
     random       = self.random_1_0_1_1;         # 7.4.1 ok
     cabalInstall = self.cabalInstall_0_14_0;    # 7.4.1 ok
     alex         = self.alex_3_0_1;             # 7.4.1 ok