diff --git a/.github/workflows/check-build.yml b/.github/workflows/check-build.yml
index 9bb32f6..698f148 100644
--- a/.github/workflows/check-build.yml
+++ b/.github/workflows/check-build.yml
@@ -108,3 +108,38 @@ jobs:
       if: ${{ !steps.cache-nix-store-emacsGit.outputs.cache-hit }}
       run: |
         nix-store --export $(nix-store -qR /nix/store/*-doom-emacs) > nix-store.dump
+  check-splitdir:
+    name: Flake Check splitdir (x86_64 only)
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v3
+      with:
+          # Nix Flakes doesn't work on shallow clones
+          fetch-depth: 0
+    - uses: cachix/install-nix-action@v17
+      with:
+        extra_nix_config: |
+          extra-substituters = https://nix-community.cachix.org
+          extra-trusted-public-keys = nix-community.cachix.org-1:mB9FSh9qf2dCimDSUo8Zy7bkq5CX+/rkCWyvRCYg3Fs=
+    - name: Retrieve /nix/store archive
+      uses: actions/cache@v3
+      id: cache-nix-store
+      with:
+        path: nix-store.dump
+        key: nix-store-${{ hashFiles('flake.lock') }}
+        restore-keys: |
+          nix-store-
+    - name: Import /nix/store contents
+      if: ${{ steps.cache-nix-store.outputs.cache-hit }}
+      run: |
+        if [[ -f nix-store.dump ]]; then
+          nix-store --import < nix-store.dump || true
+          rm nix-store.dump
+        fi
+    - name: Run checks in emacs
+      run: |
+        nix build .#checks.x86_64-linux.init-example-el-splitdir
+    - name: Export /nix/store contents
+      if: ${{ !steps.cache-nix-store.outputs.cache-hit }}
+      run: |
+        nix-store --export $(nix-store -qR /nix/store/*-doom-emacs) > nix-store.dump
diff --git a/checks.nix b/checks.nix
index d12a28d..e48599f 100644
--- a/checks.nix
+++ b/checks.nix
@@ -41,4 +41,26 @@ in
     dependencyOverrides = inputs;
     emacsPackages = with pkgs; emacsPackagesFor emacsGit;
   };
+  init-example-el-splitdir = self.outputs.package.${system} {
+    dependencyOverrides = inputs;
+    doomPrivateDir = pkgs.linkFarm "my-doom-packages" [
+         { name = "config.el"; path = ./test/doom.d/config.el; }
+         { name = "init.el"; path = ./test/doom.d/init.el; }
+         # Should *not* fail because we're building our straight environment
+         # using the doomPackageDir, not the doomPrivateDir.
+         {
+           name = "packages.el";
+           path = pkgs.writeText "packages.el" "(package! not-a-valid-package)";
+         }
+       ];
+    doomPackageDir = pkgs.linkFarm "my-doom-packages" [
+         # straight needs a (possibly empty) `config.el` file to build
+         { name = "config.el"; path = pkgs.emptyFile; }
+         { name = "init.el"; path = ./test/doom.d/init.el; }
+         {
+           name = "packages.el";
+           path = pkgs.writeText "packages.el" "(package! inheritenv)";
+         }
+       ];
+  };
 }
diff --git a/default.nix b/default.nix
index 0b712bf..68aa633 100644
--- a/default.nix
+++ b/default.nix
@@ -13,11 +13,14 @@
          # straight needs a (possibly empty) `config.el` file to build
          { name = "config.el"; path = pkgs.emptyFile; }
          { name = "init.el"; path = ./doom.d/init.el; }
-         { name = "packages.el"; path = pkgs.writeText "(package! inheritenv)"; }
+         {
+           name = "packages.el";
+           path = pkgs.writeText "packages.el" "(package! inheritenv)";
+         }
          { name = "modules"; path = ./my-doom-module; }
        ];
    */
-,  doomPackageDir ? null
+,  doomPackageDir ? doomPrivateDir
   /* Extra packages to install
 
      Useful for non-emacs packages containing emacs bindings (e.g.
@@ -123,8 +126,6 @@ let
   # Bundled version of `emacs-overlay`
   emacs-overlay = import (lock "emacs-overlay") pkgs pkgs;
 
-  doomPackageInstallDir = if doomPackageDir == null then doomPrivateDir else doomPackageDir;
-
   # Stage 2: install dependencies and byte-compile prepared source
   doomLocal = let
     straight-env = pkgs.callPackage (lock "nix-straight") {
@@ -146,7 +147,7 @@ let
       phases = [ "installPhase" ];
       nativeBuildInputs = [ git ];
       preInstall = ''
-        export DOOMDIR=${doomPackageInstallDir}
+        export DOOMDIR=${doomPackageDir}
         export DOOMLOCALDIR=$(mktemp -d)/local/
       '';
     });
@@ -164,7 +165,7 @@ let
     phases = [ "installPhase" ];
     nativeBuildInputs = [ git ];
     preInstall = ''
-      export DOOMDIR=${doomPackageInstallDir}
+      export DOOMDIR=${doomPackageDir}
       export DOOMLOCALDIR=$out/
 
       # Create a bogus $HOME directory because gccEmacs is known to require