diff --git a/lib/code-examples.js b/lib/code-examples.js
index dc17640..75ca02d 100644
--- a/lib/code-examples.js
+++ b/lib/code-examples.js
@@ -13,7 +13,7 @@ export default {
   .create(observer => {
     let n = 1;
 
-    setInterval(() => {
+    const intervalId = setInterval(() => {
       if (Math.random() < 0.8 && n < 9) {
         observer.next(n * n);
         n += 1;
@@ -21,6 +21,8 @@ export default {
         observer.error('Oh no...');
       }
     }, 1000);
+
+    return () => clearInterval(intervalId);
   })
 `,
     timeWindow: 10000
@@ -56,7 +58,7 @@ Rx.Observable.zip(
   .create(observer => {
     let secondLast = 1, last = 0;
 
-    setInterval(() => {
+    const intervalId = setInterval(() => {
       const next = secondLast + last;
 
       observer.next(next);
@@ -64,6 +66,8 @@ Rx.Observable.zip(
       secondLast = last;
       last = next;
     }, 1000);
+
+    return () => clearInterval(intervalId);
   })
   .delay(100)
   .groupBy(n => Math.floor(Math.log10(n)))