diff --git a/package.json b/package.json
index b71b92ac1..22aab8f25 100644
--- a/package.json
+++ b/package.json
@@ -113,6 +113,7 @@
         "@semantic-release/git",
         {
           "assets": [
+            "package.json",
             "docs",
             "CHANGELOG.md"
           ],
diff --git a/test/integration/liquid/fs-option.ts b/test/integration/liquid/fs-option.ts
index 2ab424de3..be68f35ae 100644
--- a/test/integration/liquid/fs-option.ts
+++ b/test/integration/liquid/fs-option.ts
@@ -4,9 +4,12 @@ import { Liquid } from '../../../src/liquid'
 describe('LiquidOptions#fs', function () {
   let engine: Liquid
   const fs = {
-    exists: () => Promise.resolve(true),
-    readFile: () => Promise.resolve('test file content'),
-    resolve: () => 'resolved'
+    exists: (x: string) => Promise.resolve(x.match(/^\/root\/files\//)),
+    existsSync: (x: string) => x.match(/^\/root\/files\//),
+    readFile: (x: string) => Promise.resolve(`content for ${x}`),
+    readFileSync: (x: string) => `content for ${x}`,
+    fallback: (x: string) => '/root/files/fallback',
+    resolve: (base: string, path: string) => base + path
   }
   beforeEach(function () {
     engine = new Liquid({
@@ -14,8 +17,18 @@ describe('LiquidOptions#fs', function () {
       fs
     } as any)
   })
-  it('should be used to read templates', function () {
-    return engine.renderFile('files/foo')
-      .then(x => expect(x).to.equal('test file content'))
+  it('should be used to read templates', async function () {
+    const html = await engine.renderFile('files/foo')
+    expect(html).to.equal('content for /root/files/foo')
+  })
+
+  it('should support fallback', async function () {
+    const html = await engine.renderFile('notexist/foo')
+    expect(html).to.equal('content for /root/files/fallback')
+  })
+
+  it('should support renderSync', function () {
+    const html = engine.renderFileSync('notexist/foo')
+    expect(html).to.equal('content for /root/files/fallback')
   })
 })