diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index 9b2ebf6..2518d15 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -19,4 +19,4 @@ jobs:
     - uses: actions/checkout@v2
     - uses: cachix/install-nix-action@v14
     - name: build
-      run: NIX_PATH=nixpkgs=https://github.com/NixOS/nixpkgs/archive/nixpkgs-unstable.tar.gz nix-build
+      run: NIX_PATH=nixpkgs=https://github.com/NixOS/nixpkgs/archive/nixpkgs-unstable.tar.gz nix-build --expr '(import <nixpkgs> { }).callPackage ./. { }'