diff --git a/.github/workflows/test-flakes.yml b/.github/workflows/test-flakes.yml
index 75e8e2f..959bfae 100644
--- a/.github/workflows/test-flakes.yml
+++ b/.github/workflows/test-flakes.yml
@@ -19,7 +19,7 @@ jobs:
           fetch-depth: 0
     - uses: cachix/install-nix-action@v14
       with:
-        install_url: https://github.com/numtide/nix-flakes-installer/releases/download/nix-2.4pre20210207_fd6eaa1/install
+        install_url: https://github.com/numtide/nix-unstable-installer/releases/download/nix-2.4pre20210823_af94b54/install
         extra_nix_config: |
           experimental-features = nix-command flakes
           system-features = nixos-test benchmark big-parallel kvm