diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index a66627b..b6ea029 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -17,6 +17,8 @@ jobs:
         uses: cachix/install-nix-action@v17
       - name: Prepare devShell
         run: nix develop --command true
+      - name: Install NPM packages
+        run: nix develop --command npm ci
       - name: Run pre-commit
         run: nix develop --command pre-commit
 
diff --git a/flake.nix b/flake.nix
index 9979322..785d76a 100644
--- a/flake.nix
+++ b/flake.nix
@@ -143,7 +143,7 @@
         })
     // {
       overlays = {
-        default = lib.composeExtension self.overlays.nil self.overlays.coc-nil;
+        default = lib.composeExtensions self.overlays.nil self.overlays.coc-nil;
         nil = final: prev: {
           nil = final.callPackage mkNil { };
         };