diff --git a/lib/cli/init.js b/lib/cli/init.js
index 3847aff86c..8eb5f0ab89 100644
--- a/lib/cli/init.js
+++ b/lib/cli/init.js
@@ -24,12 +24,12 @@ exports.handler = argv => {
   const destdir = argv.path;
   const srcdir = path.join(__dirname, '..', '..');
   fs.mkdirSync(destdir, {recursive: true});
-  const css = fs.readFileSync(path.join(srcdir, 'mocha.css'));
+  const css = fs.readFileSync(path.join(srcdir, 'mocha.sass'));
   const js = fs.readFileSync(path.join(srcdir, 'mocha.js'));
   const tmpl = fs.readFileSync(
     path.join(srcdir, 'lib', 'browser', 'template.html')
   );
-  fs.writeFileSync(path.join(destdir, 'mocha.css'), css);
+  fs.writeFileSync(path.join(destdir, 'mocha.sass'), css);
   fs.writeFileSync(path.join(destdir, 'mocha.js'), js);
   fs.writeFileSync(path.join(destdir, 'tests.spec.js'), '');
   fs.writeFileSync(path.join(destdir, 'index.html'), tmpl);
diff --git a/package.json b/package.json
index d0dcd763bf..657cfed075 100644
--- a/package.json
+++ b/package.json
@@ -168,7 +168,7 @@
     "assets/growl/*.png",
     "lib/**/*.{js,html,json}",
     "index.js",
-    "mocha.css",
+    "mocha.sass",
     "mocha.js",
     "mocha.js.map",
     "mocha-es2018.js",
diff --git a/test/integration/init.spec.js b/test/integration/init.spec.js
index 3961b27844..c925793bcb 100644
--- a/test/integration/init.spec.js
+++ b/test/integration/init.spec.js
@@ -66,7 +66,7 @@ describe('init command', function() {
           return done(err);
         }
         expect(result, 'to have succeeded');
-        expect(fs.existsSync(path.join(tmpdir, 'mocha.css')), 'to be true');
+        expect(fs.existsSync(path.join(tmpdir, 'mocha.sass')), 'to be true');
         expect(fs.existsSync(path.join(tmpdir, 'mocha.js')), 'to be true');
         expect(fs.existsSync(path.join(tmpdir, 'tests.spec.js')), 'to be true');
         expect(fs.existsSync(path.join(tmpdir, 'index.html')), 'to be true');