diff --git a/.github/workflows/editorconfig.yml b/.github/workflows/editorconfig.yml
index 9fe857e..57a0177 100644
--- a/.github/workflows/editorconfig.yml
+++ b/.github/workflows/editorconfig.yml
@@ -4,6 +4,7 @@ permissions: read-all
 
 on:
   push:
+    branches: [master]
   pull_request:
 
 jobs:
@@ -11,7 +12,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
     - uses: actions/checkout@v3
-    - uses: cachix/install-nix-action@v20
+    - uses: cachix/install-nix-action@v24
     - name: "Check EditorConfig"
       # Python already has Ruff,
       # and doesn't necessarily have a consistent 4 spaces indent
diff --git a/.github/workflows/nix-build.yml b/.github/workflows/nix-build.yml
new file mode 100644
index 0000000..88f4306
--- /dev/null
+++ b/.github/workflows/nix-build.yml
@@ -0,0 +1,22 @@
+name: "Nix build"
+
+permissions: read-all
+
+on:
+  # Allows running this workflow manually
+  workflow_dispatch:
+  push:
+    branches: [master]
+  pull_request:
+
+jobs:
+  nix-build:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: cachix/install-nix-action@v24
+      - uses: DeterminateSystems/magic-nix-cache-action@v2
+        with:
+          diagnostic-endpoint: ""
+      - name: Run `nix build`
+        run: nix build -L .
diff --git a/.github/workflows/ruff.yml b/.github/workflows/ruff.yml
index c92426a..acbb72a 100644
--- a/.github/workflows/ruff.yml
+++ b/.github/workflows/ruff.yml
@@ -1,9 +1,10 @@
-name: "Check Formatting"
+name: "Ruff lints"
 
 permissions: read-all
 
 on:
   push:
+    branches: [master]
   pull_request:
 
 jobs:
@@ -11,6 +12,13 @@ jobs:
     runs-on: ubuntu-latest
     steps:
     - uses: actions/checkout@v3
-    - uses: cachix/install-nix-action@v20
+    - name: Get changed files
+      id: changed-files
+      uses: tj-actions/changed-files@v40
+      with:
+        files: |
+            **.py
+    - uses: cachix/install-nix-action@v24
     - name: "Check Ruff lints"
-      run: nix run 'nixpkgs#ruff' -- check . --output-format=github
+      if: steps.changed-files.outputs.any_changed == 'true'
+      run: nix run 'nixpkgs#ruff' -- check . --output-format=github ${{ steps.changed-files.outputs.all_changed_files }}