diff --git a/pkgs/development/libraries/haskell/mtl/1.1.1.1.nix b/pkgs/development/libraries/haskell/mtl/1.1.1.1.nix
deleted file mode 100644
index d7e6029a4ed..00000000000
--- a/pkgs/development/libraries/haskell/mtl/1.1.1.1.nix
+++ /dev/null
@@ -1,13 +0,0 @@
-{ cabal }:
-
-cabal.mkDerivation (self: {
-  pname = "mtl";
-  version = "1.1.1.1";
-  sha256 = "157gbrgrg0l9r72nq45dkach53yncysif4qglsaql28g37djc4x6";
-  meta = {
-    description = "Monad transformer library";
-    license = self.stdenv.lib.licenses.bsd3;
-    platforms = self.ghc.meta.platforms;
-    maintainers = [ self.stdenv.lib.maintainers.andres ];
-  };
-})
diff --git a/pkgs/development/libraries/haskell/mtl/2.1.3.1.nix b/pkgs/development/libraries/haskell/mtl/2.2.1.nix
similarity index 81%
rename from pkgs/development/libraries/haskell/mtl/2.1.3.1.nix
rename to pkgs/development/libraries/haskell/mtl/2.2.1.nix
index e9fa49510c1..e7147b28767 100644
--- a/pkgs/development/libraries/haskell/mtl/2.1.3.1.nix
+++ b/pkgs/development/libraries/haskell/mtl/2.2.1.nix
@@ -2,8 +2,8 @@
 
 cabal.mkDerivation (self: {
   pname = "mtl";
-  version = "2.1.3.1";
-  sha256 = "1xpn2wjmqbh2cg1yssc6749xpgcqlrrg4iilwqgkcjgvaxlpdbvp";
+  version = "2.2.1";
+  sha256 = "1icdbj2rshzn0m1zz5wa7v3xvkf6qw811p4s7jgqwvx1ydwrvrfa";
   buildDepends = [ transformers ];
   meta = {
     homepage = "http://github.com/ekmett/mtl";
diff --git a/pkgs/top-level/haskell-defaults.nix b/pkgs/top-level/haskell-defaults.nix
index d07544691e6..697004c02fb 100644
--- a/pkgs/top-level/haskell-defaults.nix
+++ b/pkgs/top-level/haskell-defaults.nix
@@ -15,7 +15,7 @@
   # Older compilers inherit the overrides from newer ones.
 
   ghcHEADPrefs = self : super : super // {
-    mtl = self.mtl_2_1_3_1;
+    mtl = self.mtl_2_2_1;
     cabalInstall_1_20_0_2 = super.cabalInstall_1_20_0_2.override { Cabal = null; };
   };
 
diff --git a/pkgs/top-level/haskell-packages.nix b/pkgs/top-level/haskell-packages.nix
index 724dffd69ef..ceeee5caeab 100644
--- a/pkgs/top-level/haskell-packages.nix
+++ b/pkgs/top-level/haskell-packages.nix
@@ -1482,12 +1482,10 @@ self : let callPackage = x : y : modifyPrio (newScope self x y); in
   msgpack = callPackage ../development/libraries/haskell/msgpack {};
 
   mtl_1_1_0_2 = callPackage ../development/libraries/haskell/mtl/1.1.0.2.nix {};
-  mtl_1_1_1_1 = callPackage ../development/libraries/haskell/mtl/1.1.1.1.nix {};
   mtl_2_0_1_0 = callPackage ../development/libraries/haskell/mtl/2.0.1.0.nix {};
   mtl_2_1_1 = callPackage ../development/libraries/haskell/mtl/2.1.1.nix {};
   mtl_2_1_2 = callPackage ../development/libraries/haskell/mtl/2.1.2.nix {};
-  mtl_2_1_3_1 = callPackage ../development/libraries/haskell/mtl/2.1.3.1.nix {};
-  mtl_2_2_0_1 = callPackage ../development/libraries/haskell/mtl/2.2.0.1.nix {};
+  mtl_2_2_1 = callPackage ../development/libraries/haskell/mtl/2.2.1.nix {};
   mtl = null; # tightly coupled with 'transformers' which is a core package
 
   mtlparse = callPackage ../development/libraries/haskell/mtlparse {};