diff --git a/overlay.nix b/overlay.nix
index fa0e296ee1a41242c3438b4444c56666d7c4e64d..9260f09f7731700e526fbb785c7a10d41bc23419 100644
--- a/overlay.nix
+++ b/overlay.nix
@@ -151,6 +151,8 @@ final: prev: with pkgs.haskell.lib; {
 
   generics-sop = prev.callHackage "generics-sop" "0.5.1.2" { };
 
+  genvalidity-hspec = prev.callHackage "genvalidity-hspec" "1.0.0.2" { };
+
   ghc-check = dontHaddock (prev.callHackage "ghc-check" "0.5.0.8" { });
 
   ghc-byteorder = doJailbreak (prev.callHackage "ghc-byteorder" "4.11.0.0.10" { });