diff --git a/pkgs/development/libraries/haskell/monad-unify/default.nix b/pkgs/development/libraries/haskell/monad-unify/default.nix
new file mode 100644
index 000000000000..7ee1f8c87040
--- /dev/null
+++ b/pkgs/development/libraries/haskell/monad-unify/default.nix
@@ -0,0 +1,13 @@
+{ cabal, mtl, unorderedContainers }:
+
+cabal.mkDerivation (self: {
+  pname = "monad-unify";
+  version = "0.2.2";
+  sha256 = "1icl4jaa4vc4lb75m6wv4vjvf8b2xx7aziqhsg2pshizdkfxmgwp";
+  buildDepends = [ mtl unorderedContainers ];
+  meta = {
+    description = "Generic first-order unification";
+    license = self.stdenv.lib.licenses.mit;
+    platforms = self.ghc.meta.platforms;
+  };
+})
diff --git a/pkgs/top-level/haskell-packages.nix b/pkgs/top-level/haskell-packages.nix
index 216037e74cdf..11f0278c20f8 100644
--- a/pkgs/top-level/haskell-packages.nix
+++ b/pkgs/top-level/haskell-packages.nix
@@ -1442,6 +1442,8 @@ self : let callPackage = x : y : modifyPrio (newScope self x y); in
 
   monadsTf = callPackage ../development/libraries/haskell/monads-tf {};
 
+  monadUnify = callPackage ../development/libraries/haskell/monad-unify {};
+
   monoidExtras = callPackage ../development/libraries/haskell/monoid-extras {};
 
   monoidTransformer = callPackage ../development/libraries/haskell/monoid-transformer {};