diff --git a/build-helpers/doomscript.nix b/build-helpers/doomscript.nix
new file mode 100644
index 0000000..853402a
--- /dev/null
+++ b/build-helpers/doomscript.nix
@@ -0,0 +1,42 @@
+# Copyright 2024 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+{
+  script,
+  scriptArgs,
+  doomSource,
+  debug ? false,
+  name ? "doomscript",
+  extraArgs ? { },
+
+  emacs,
+  lib,
+  runCommandLocal,
+  runtimeShell,
+}:
+runCommandLocal name
+  (
+    {
+      inherit doomSource runtimeShell script;
+      EMACS = lib.getExe emacs;
+    }
+    // (lib.optionalAttrs debug { DEBUG = "1"; })
+    // extraArgs
+  )
+  # Set DOOMLOCALDIR somewhere harmless to stop Doom from trying to create it somewhere read-only.
+  ''
+    mkdir $out
+    export DOOMLOCALDIR=$(mktemp -d)
+    $runtimeShell $doomSource/bin/doomscript $script ${scriptArgs}
+  ''
diff --git a/default.nix b/default.nix
index 95238f2..71b5f5e 100644
--- a/default.nix
+++ b/default.nix
@@ -41,6 +41,7 @@
   /* Extra emacs packages from nixpkgs */
   extraPackages ? epkgs: [ ],
 
+  callPackage,
   callPackages,
   git,
   emacsPackagesFor,
@@ -57,37 +58,19 @@ let
 
   # This doesn't belong here: it does not depend on doomDir (only on doomSource).
   # But this is where all my doomscript execution lives.
-  # TODO: consider splitting off doomdir execution to a separate helper.
-  doomDirWithAllModules = runCommandLocal "doom-full-init"
-    {
-      env = {
-        EMACS = lib.getExe emacs;
-        # Enable this to troubleshoot failures at this step.
-        #DEBUG = "1";
-      };
-      # We set DOOMLOCALDIR somewhere harmless below to stop Doom from trying to
-      # create it somewhere read-only.
-    } ''
-    mkdir $out
-    export DOOMLOCALDIR=$(mktemp -d)
-    ${runtimeShell} ${doomSource}/bin/doomscript ${./build-helpers/full-init} -o $out
-  '';
-
-  doomDirWithAllModulesAndFlags = runCommandLocal "doom-full-init"
-    {
-      env = {
-        EMACS = lib.getExe emacs;
-        # Enable this to troubleshoot failures at this step.
-        #DEBUG = "1";
-      };
-      # We set DOOMLOCALDIR somewhere harmless below to stop Doom from trying to
-      # create it somewhere read-only.
-    } ''
-    mkdir $out
-    export DOOMLOCALDIR=$(mktemp -d)
-    ${runtimeShell} ${doomSource}/bin/doomscript ${./build-helpers/full-init} --flags -o $out
-  '';
+  doomDirWithAllModules = callPackage ./build-helpers/doomscript.nix {
+    name = "doom-full-init";
+    inherit doomSource emacs;
+    script = ./build-helpers/full-init;
+    scriptArgs = "-o $out";
+  };
 
+  doomDirWithAllModulesAndFlags = callPackage ./build-helpers/doomscript.nix {
+    name = "doom-full-init";
+    inherit doomSource emacs;
+    script = ./build-helpers/full-init;
+    scriptArgs = "--flags -o $out";
+  };
 
   # Step 1: determine which Emacs packages to pull in.
   #
@@ -100,21 +83,13 @@ let
   # (not even straight).
 
   # Force local build in case the user init.el does something weird and to avoid a roundtrip.
-  doomIntermediates = runCommandLocal "doom-intermediates"
-    {
-      env = {
-        EMACS = lib.getExe emacs;
-        DOOMDIR = "${doomDir}";
-        # Enable this to troubleshoot failures at this step.
-        #DEBUG = "1";
-      };
-      # We set DOOMLOCALDIR somewhere harmless below to stop Doom from trying to
-      # create it somewhere read-only.
-    } ''
-    mkdir $out
-    export DOOMLOCALDIR=$(mktemp -d)
-    ${runtimeShell} ${doomSource}/bin/doomscript ${./build-helpers/dump} -o $out
-  '';
+  doomIntermediates = callPackage ./build-helpers/doomscript.nix {
+    name = "doom-intermediates";
+    inherit doomSource emacs;
+    extraArgs = { DOOMDIR = "${doomDir}"; };
+    script = ./build-helpers/dump;
+    scriptArgs = "-o $out";
+  };
 
   doomPackageSet = lib.importJSON "${doomIntermediates}/packages.json";