diff --git a/overrides/writeElispBin/default.nix b/nix/writeElispBin/default.nix
similarity index 86%
rename from overrides/writeElispBin/default.nix
rename to nix/writeElispBin/default.nix
index 1b3ba0544..c116607e0 100644
--- a/overrides/writeElispBin/default.nix
+++ b/nix/writeElispBin/default.nix
@@ -1,6 +1,6 @@
 { depot, pkgs, ... }:
 
-{ name, src, deps ? (_: []), emacs ? pkgs.emacs26-nox }:
+{ name, src, deps ? (_: []), emacs ? pkgs.emacs27-nox }:
 
 let
   inherit (pkgs) emacsPackages emacsPackagesGen;
diff --git a/users/tazjin/aoc2019/default.nix b/users/tazjin/aoc2019/default.nix
index 5f1f248c5..ce3146d1f 100644
--- a/users/tazjin/aoc2019/default.nix
+++ b/users/tazjin/aoc2019/default.nix
@@ -13,7 +13,7 @@ let
   solutionFiles = filter (e: dir."${e}" == "regular" && isSolution e) (attrNames dir);
   solutions = map (f: let day = getDay f; in {
     name = day;
-    value = depot.writeElispBin { # TODO(tazjin): move writeElispBin to depot.nix
+    value = depot.nix.writeElispBin {
       name = "aoc2019";
       deps = p: with p; [ dash s ht ];
       src = ./. + ("/" + f);