diff --git a/.github/workflows/nix-parse-v2.yml b/.github/workflows/nix-parse-v2.yml
index cc988e20bd6e..706cc34619bb 100644
--- a/.github/workflows/nix-parse-v2.yml
+++ b/.github/workflows/nix-parse-v2.yml
@@ -15,18 +15,6 @@ jobs:
     needs: get-merge-commit
     if: "needs.get-merge-commit.outputs.mergedSha && !contains(github.event.pull_request.title, '[skip treewide]')"
     steps:
-      - name: Get list of changed files from PR
-        env:
-          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
-        run: |
-          gh api \
-            repos/${{ github.repository }}/pulls/${{github.event.number}}/files --paginate \
-            | jq --raw-output '.[] | select(.status != "removed" and (.filename | endswith(".nix"))) | .filename' \
-            > "$HOME/changed_files"
-          if [[ -s "$HOME/changed_files" ]]; then
-            echo "CHANGED_FILES=$HOME/changed_files" > "$GITHUB_ENV"
-          fi
-
       - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
         with:
           ref: ${{ needs.get-merge-commit.outputs.mergedSha }}
@@ -37,11 +25,6 @@ jobs:
           extra_nix_config: sandbox = true
           nix_path: nixpkgs=channel:nixpkgs-unstable
 
-      - name: Parse all changed or added nix files
+      - name: Parse all nix files
         run: |
-          ret=0
-          while IFS= read -r file; do
-            out="$(nix-instantiate --parse "$file")" || { echo "$out" && ret=1; }
-          done < "$HOME/changed_files"
-          exit "$ret"
-        if: ${{ env.CHANGED_FILES && env.CHANGED_FILES != '' }}
+          nix-build ci -A parse
diff --git a/ci/default.nix b/ci/default.nix
index 396fb172df23..67b1eddf1000 100644
--- a/ci/default.nix
+++ b/ci/default.nix
@@ -76,5 +76,8 @@ in
   manual-nixos = (import ../nixos/release.nix { }).manual.${system} or null;
   manual-nixpkgs = (import ../pkgs/top-level/release.nix { }).manual;
   manual-nixpkgs-tests = (import ../pkgs/top-level/release.nix { }).manual.tests;
+  parse = pkgs.lib.recurseIntoAttrs {
+    latest = pkgs.callPackage ./parse.nix { nix = pkgs.nixVersions.latest; };
+  };
   shell = import ../shell.nix { inherit nixpkgs system; };
 }
diff --git a/ci/parse.nix b/ci/parse.nix
new file mode 100644
index 000000000000..26ac0f785fd4
--- /dev/null
+++ b/ci/parse.nix
@@ -0,0 +1,43 @@
+{
+  lib,
+  nix,
+  runCommand,
+}:
+let
+  nixpkgs =
+    with lib.fileset;
+    toSource {
+      root = ../.;
+      fileset = (fileFilter (file: file.hasExt "nix") ../.);
+    };
+in
+runCommand "nix-parse-${nix.name}"
+  {
+    nativeBuildInputs = [
+      nix
+    ];
+  }
+  ''
+    export NIX_STORE_DIR=$TMPDIR/store
+    export NIX_STATE_DIR=$TMPDIR/state
+
+    cd "${nixpkgs}"
+
+    # Passes all files to nix-instantiate at once.
+    # Much faster, but will only show first error.
+    parse-all() {
+      find . -type f -iname '*.nix' | xargs -P $(nproc) nix-instantiate --parse >/dev/null 2>/dev/null
+    }
+
+    # Passes each file separately to nix-instantiate with -n1.
+    # Much slower, but will show all errors.
+    parse-each() {
+      find . -type f -iname '*.nix' | xargs -n1 -P $(nproc) nix-instantiate --parse >/dev/null
+    }
+
+    if ! parse-all; then
+      parse-each
+    fi
+
+    touch $out
+  ''