diff --git a/package.json b/package.json
index 2eb6e1d4..b4164ed9 100644
--- a/package.json
+++ b/package.json
@@ -48,6 +48,6 @@
     "ts-node": "^7.0.1",
     "tslib": "^1.9.3",
     "tslint": "^4.5.1",
-    "typescript": "^3.0.3"
+    "typescript": "^3.4.1"
   }
 }
diff --git a/test/integration.ts b/test/integration.ts
index 387b7ee7..8edcebee 100644
--- a/test/integration.ts
+++ b/test/integration.ts
@@ -8,6 +8,7 @@ import * as rollup from 'rollup';
 import typescript = require('rollup-plugin-typescript');
 import { assert } from 'chai';
 import { SnapshotState, toMatchSnapshot } from 'jest-snapshot';
+import { Suite } from 'mocha';
 
 const htmlFolder = path.join(__dirname, 'html');
 const htmls = fs.readdirSync(htmlFolder).map(filePath => {
@@ -23,7 +24,7 @@ interface IMimeType {
 }
 
 const server = () =>
-  new Promise(resolve => {
+  new Promise<http.Server>(resolve => {
     const mimeType: IMimeType = {
       '.html': 'text/html',
       '.js': 'text/javascript',
@@ -66,7 +67,13 @@ function matchSnapshot(actual: string, testFile: string, testTitle: string) {
   return result;
 }
 
-describe('integration tests', () => {
+interface ISuite extends Suite {
+  server: http.Server;
+  browser: puppeteer.Browser;
+  code: string;
+}
+
+describe('integration tests', function(this: ISuite) {
   before(async () => {
     this.server = await server();
     this.browser = await puppeteer.launch({
diff --git a/test/snapshot.test.ts b/test/snapshot.test.ts
index 9a29018d..c2f736f9 100644
--- a/test/snapshot.test.ts
+++ b/test/snapshot.test.ts
@@ -54,7 +54,7 @@ describe('absolute url to stylesheet', () => {
         href,
       ),
     ).to.equal(
-      `background-image: url('http://localhost/css/images/b.jpg'); ` +
+      `background-image: url('http://localhost/css/images/b.jpg');` +
         `background: #aabbcc url('http://localhost/css/images/a.jpg') 50% 50% repeat;`,
     );
   });