diff --git a/horizon.dhall b/horizon.dhall
index 70e2cfaacdd59d9863ce871d0f2962042bd1365d..231ee171f47d3f0b58816255e7cf1a5becc486d9 100644
--- a/horizon.dhall
+++ b/horizon.dhall
@@ -547,7 +547,7 @@ let packages =
       , hls-test-utils = H.callHackage "hls-test-utils" "1.5.0.0"
       , hopenssl = H.callHackage "hopenssl" "2.2.4"
       , horizon-gen-nix = H.callHackage "horizon-gen-nix" "0.6"
-      , horizon-spec = H.callHackage "horizon-spec" "0.6.1"
+      , horizon-spec = H.callHackage "horizon-spec" "0.6.4"
       , horizon-spec-lens = H.callHackage "horizon-spec-lens" "0.1"
       , horizon-spec-pretty = H.callHackage "horizon-spec-pretty" "0.0.1"
       , hosc = H.callHackage "hosc" "0.19.1"
diff --git a/pkgs/horizon-spec.nix b/pkgs/horizon-spec.nix
index 00087fe6a40a45a3540f285b197cdab7f4dc80f9..cea22c252d0688ffe8ca03b38303bb6f2a5161a4 100644
--- a/pkgs/horizon-spec.nix
+++ b/pkgs/horizon-spec.nix
@@ -7,12 +7,14 @@
 , path-dhall-instance
 , prettyprinter
 , sydtest
+, template-haskell
 , text
+, th-lift
 }:
 mkDerivation {
   pname = "horizon-spec";
-  version = "0.6.1";
-  sha256 = "97840918baa16cc175560645d1cd3bf762f7b6133d9c44f1c4da152431f65ada";
+  version = "0.6.4";
+  sha256 = "092aff7d396d331dbe45414e40fa5a142e8c47a4df8f141aa493cce5437fb72f";
   isLibrary = true;
   isExecutable = true;
   enableSeparateDataOutput = false;
@@ -22,7 +24,9 @@ mkDerivation {
     dhall
     path
     path-dhall-instance
+    template-haskell
     text
+    th-lift
   ];
   executableHaskellDepends = [
     base