diff --git a/horizon.dhall b/horizon.dhall
index b902870f0232fa68a41df7281a4ee40db6c3213f..89304461a80f3bc829d49d8d046403a38f05e8e8 100644
--- a/horizon.dhall
+++ b/horizon.dhall
@@ -110,6 +110,7 @@ let otherLibraries =
       , H.callHackage "HTF" "0.15.0.0"
       , H.callHackage "HsOpenSSL" "0.11.7.2"
       , H.callHackage "MemoTrie" "0.6.10"
+      , H.callHackage "NumInstances" "1.4"
       , H.callHackage "PyF" "0.11.0.0"
       , H.callHackage "Stream" "0.4.7.2"
       , H.callHackage "Unique" "0.4.7.9"
diff --git a/overlay.nix b/overlay.nix
index 3d1c37a4585118e60faabd5ef48b06aea16452d5..e83500f8fd0b9d3867d7215e5e605ab96074ca69 100644
--- a/overlay.nix
+++ b/overlay.nix
@@ -9,6 +9,8 @@ final: prev: with pkgs.haskell.lib; {
 
   MemoTrie = final.callPackage (./pkgs/MemoTrie.nix) { };
 
+  NumInstances = final.callPackage (./pkgs/NumInstances.nix) { };
+
   PyF = final.callPackage (./pkgs/PyF.nix) { };
 
   Stream = final.callPackage (./pkgs/Stream.nix) { };
diff --git a/pkgs/NumInstances.nix b/pkgs/NumInstances.nix
new file mode 100644
index 0000000000000000000000000000000000000000..e43097322cbf3b749f19fd3815a1695590bbfd19
--- /dev/null
+++ b/pkgs/NumInstances.nix
@@ -0,0 +1,21 @@
+{ mkDerivation, base, lib }:
+mkDerivation {
+  pname = "NumInstances";
+  version = "1.4";
+  sha256 = "cbdb2a49346f59ceb5ab38592d7bc52e5205580d431d0ac6d852fd9880e59679";
+  isLibrary = true;
+  isExecutable = false;
+  enableSeparateDataOutput = false;
+  libraryHaskellDepends = [ base ];
+  enableLibraryProfiling = true;
+  enableExecutableProfiling = true;
+  doHaddock = false;
+  jailbreak = true;
+  doCheck = false;
+  doBenchmark = false;
+  hyperlinkSource = false;
+  homepage = "https://github.com/conal/NumInstances";
+  description = "Instances of numeric classes for functions and tuples";
+  license = lib.licenses.bsd3;
+  broken = false;
+}