diff --git a/pkgs/development/compilers/carp/default.nix b/pkgs/development/compilers/carp/default.nix
index b22f5c756aba..e02880b314eb 100644
--- a/pkgs/development/compilers/carp/default.nix
+++ b/pkgs/development/compilers/carp/default.nix
@@ -1,6 +1,6 @@
 { stdenv, fetchFromGitHub, makeWrapper, clang, haskellPackages }:
 
-haskellPackages.mkDerivation {
+haskellPackages.mkDerivation rec {
 
   pname = "carp";
   version = "0.3.0";