diff --git a/examples/.eslintrc.js b/examples/.eslintrc.js
index 10086986c84..235497830db 100644
--- a/examples/.eslintrc.js
+++ b/examples/.eslintrc.js
@@ -11,5 +11,6 @@ module.exports = {
      */
     "rules": {
         "indent": [2, 2, { "SwitchCase": 1, "CallExpression": {"arguments": 2}, "MemberExpression": 2, "outerIIFEBody": 0 }],
+        "strict": [2, "global"],
     }
 };
diff --git a/examples/block-images.js b/examples/block-images.js
index 469b25ac6a5..0604f3e1a97 100644
--- a/examples/block-images.js
+++ b/examples/block-images.js
@@ -14,6 +14,8 @@
  * limitations under the License.
  */
 
+'use strict';
+
 const puppeteer = require('puppeteer');
 
 (async() => {
diff --git a/examples/detect-sniff.js b/examples/detect-sniff.js
index b6727ecffc3..574cee9d9da 100644
--- a/examples/detect-sniff.js
+++ b/examples/detect-sniff.js
@@ -14,6 +14,8 @@
  * limitations under the License.
  */
 
+'use strict';
+
 const puppeteer = require('puppeteer');
 
 function sniffDetector() {
diff --git a/examples/pdf.js b/examples/pdf.js
index fb79585433b..dd5b8417cd7 100644
--- a/examples/pdf.js
+++ b/examples/pdf.js
@@ -14,6 +14,8 @@
  * limitations under the License.
  */
 
+'use strict';
+
 const puppeteer = require('puppeteer');
 
 (async() => {
diff --git a/examples/proxy.js b/examples/proxy.js
index 338eb7a9e1d..e28d26290c1 100644
--- a/examples/proxy.js
+++ b/examples/proxy.js
@@ -14,6 +14,8 @@
  * limitations under the License.
  */
 
+'use strict';
+
 const puppeteer = require('puppeteer');
 
 (async() => {
diff --git a/examples/screenshot-fullpage.js b/examples/screenshot-fullpage.js
index de74d8917fd..b5644f64858 100644
--- a/examples/screenshot-fullpage.js
+++ b/examples/screenshot-fullpage.js
@@ -14,6 +14,8 @@
  * limitations under the License.
  */
 
+'use strict';
+
 const puppeteer = require('puppeteer');
 const devices = require('puppeteer/DeviceDescriptors');
 
diff --git a/examples/screenshot.js b/examples/screenshot.js
index 73732b7fb9b..a78b038d644 100644
--- a/examples/screenshot.js
+++ b/examples/screenshot.js
@@ -14,6 +14,8 @@
  * limitations under the License.
  */
 
+'use strict';
+
 const puppeteer = require('puppeteer');
 
 (async() => {
diff --git a/examples/search.js b/examples/search.js
index 63e0365feff..5c094e34e31 100644
--- a/examples/search.js
+++ b/examples/search.js
@@ -14,6 +14,8 @@
  * limitations under the License.
  */
 
+'use strict';
+
 const puppeteer = require('puppeteer');
 
 (async() => {