diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index e49302f5..f0d29968 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -28,9 +28,10 @@ jobs:
       - uses: actions/checkout@v2
         with:
           fetch-depth: 0 # nix flakes do not work on shallow clones
-      - uses: cachix/install-nix-action@v14.1
+      - uses: cachix/install-nix-action@v15
         with:
-          extra_nix_config: experimental-features = nix-command flakes
+          extra_nix_config: |
+            access-tokens = github.com=${{ secrets.GITHUB_TOKEN }}
       - uses: cachix/cachix-action@v10
         with:
           name: cargo2nix-gh
@@ -56,37 +57,21 @@ jobs:
           nix build ./examples/4-independent-packaging# \
             --override-input cargo2nix github:cargo2nix/cargo2nix?rev=$GITHUB_SHA
           else
-          sleep 30
-          nix flake lock ./examples/1-hello-world# \
-            --override-input cargo2nix github:cargo2nix/cargo2nix?rev=$GITHUB_SHA
-          sleep 30
           nix flake lock ./examples/1-hello-world# \
+            --override-input cargo2nix github:cargo2nix/cargo2nix?rev=$GITHUB_SHA \
             --override-input nixpkgs github:nixos/nixpkgs/nixpkgs-21.05-darwin
-          sleep 30
           nix build ./examples/1-hello-world# --no-update-lock-file
-          sleep 30
-          nix flake lock ./examples/2-bigger-project# \
-            --override-input cargo2nix github:cargo2nix/cargo2nix?rev=$GITHUB_SHA
-          sleep 30
           nix flake lock ./examples/2-bigger-project# \
+            --override-input cargo2nix github:cargo2nix/cargo2nix?rev=$GITHUB_SHA \
             --override-input nixpkgs github:nixos/nixpkgs/nixpkgs-21.05-darwin
-          sleep 30
           nix build ./examples/2-bigger-project# --no-update-lock-file
-          sleep 30
           nix flake lock ./examples/3-cross-compiling# \
-            --override-input cargo2nix github:cargo2nix/cargo2nix?rev=$GITHUB_SHA
-          sleep 30
-          nix flake lock ./examples/3-cross-compiling#
+            --override-input cargo2nix github:cargo2nix/cargo2nix?rev=$GITHUB_SHA \
           #   --override-input nixpkgs github:nixos/nixpkgs/nixpkgs-21.05-darwin
-          sleep 30
           nix build ./examples/3-cross-compiling# --no-update-lock-file
-          sleep 30
-          nix flake lock ./examples/4-independent-packaging# \
-            --override-input cargo2nix github:cargo2nix/cargo2nix?rev=$GITHUB_SHA
-          sleep 30
           nix flake lock ./examples/4-independent-packaging# \
+            --override-input cargo2nix github:cargo2nix/cargo2nix?rev=$GITHUB_SHA \
             --override-input nixpkgs github:nixos/nixpkgs/nixpkgs-21.05-darwin
-          sleep 30
           nix build ./examples/4-independent-packaging# --no-update-lock-file
           fi