diff --git a/cli/packages/themer/lib/index.js b/cli/packages/themer/lib/index.js
index bc3375c..e1fb569 100644
--- a/cli/packages/themer/lib/index.js
+++ b/cli/packages/themer/lib/index.js
@@ -47,7 +47,13 @@ const path = require('path'),
       ),
     );
     console.log('rendering templates...');
-    const outputs = await themer(colors, templates, args);
+    const outputs = await themer(
+      colors,
+      templates,
+      args,
+      path.sep,
+      '# themer - theme installation instructions',
+    );
     console.log('writing files...');
     for (const output of outputs) {
       const outputFilePath = path.resolve(args.out, output.name);
diff --git a/cli/packages/themer/lib/themer.js b/cli/packages/themer/lib/themer.js
index 66fa079..eea226b 100644
--- a/cli/packages/themer/lib/themer.js
+++ b/cli/packages/themer/lib/themer.js
@@ -1,11 +1,17 @@
-module.exports = async function themer (colors, templates, extraArgs) {
+module.exports = async function themer(
+  colors,
+  templates,
+  extraArgs,
+  pathSeparator,
+  instructionsHead,
+) {
   const files = [];
   const instructions = [];
   for (const template of templates) {
     const outputs = (await Promise.all(template.render(colors, extraArgs)))
       .map(file => ({
         ...file,
-        name: `${template.name}/${file.name}`,
+        name: `${template.name}${pathSeparator}${file.name}`,
       }));
     files.push(...outputs);
     if (template.renderInstructions) {
@@ -18,7 +24,7 @@ module.exports = async function themer (colors, templates, extraArgs) {
     files.push({
       name: 'README.md',
       contents: Buffer.from(
-        `# themer - theme installation instructions\n\n${instructions.join('\n\n')}`,
+        `${instructionsHead}\n\n${instructions.join('\n\n')}`,
         'utf8'
       )
     })
diff --git a/cli/packages/themer/lib/themer.spec.js b/cli/packages/themer/lib/themer.spec.js
index c2ccb98..51c8bbd 100644
--- a/cli/packages/themer/lib/themer.spec.js
+++ b/cli/packages/themer/lib/themer.spec.js
@@ -1,4 +1,5 @@
-const themer = require('./themer');
+const themer = require('./themer'),
+  path = require('path');
 
 describe('themer core', () => {
   it('should produce a list of files from colors + templates', async () => {
@@ -34,6 +35,8 @@ describe('themer core', () => {
         },
       ],
       {},
+      path.sep,
+      '# test',
     );
     expect(outputs.length).toBe(2);
   });