diff --git a/krebs/5pkgs/default.nix b/krebs/5pkgs/default.nix
index 0ec4b3ded..7df7b7d3c 100644
--- a/krebs/5pkgs/default.nix
+++ b/krebs/5pkgs/default.nix
@@ -54,4 +54,8 @@ subdirs // rec {
     gcc -O -Wall -o "$exe" $src
     strip --strip-unneeded "$exe"
   '';
+
+  writeNixFromCabal = name: path: pkgs.runCommand name {} ''
+    ${pkgs.cabal2nix}/bin/cabal2nix ${path} > $out
+  '';
 }
diff --git a/tv/2configs/xserver/default.nix b/tv/2configs/xserver/default.nix
index 9e20bda18..facdf6df2 100644
--- a/tv/2configs/xserver/default.nix
+++ b/tv/2configs/xserver/default.nix
@@ -73,9 +73,7 @@ let
   };
 
   xmonad-pkg = pkgs.haskellPackages.callPackage xmonad-src {};
-  xmonad-src = pkgs.runCommand "xmonad-package" {} ''
-    ${pkgs.cabal2nix}/bin/cabal2nix ${./xmonad} > $out
-  '';
+  xmonad-src = pkgs.writeNixFromCabal "xmonad.nix" ./xmonad;
 
   xmonad-environment = {
     DISPLAY = ":${toString config.services.xserver.display}";