diff --git a/lib/sleep.js b/lib/sleep.js
index 061944c..3f14101 100644
--- a/lib/sleep.js
+++ b/lib/sleep.js
@@ -5,13 +5,14 @@
 // it's coming back from sleep.
 
 var EventEmitter = require('./EventEmitter');
+var timers = require('timers');
 
 var sleep = new EventEmitter();
 var frequency = 60 * 1000; // check for sleep once a minute
 var fudge = 5 * 1000;
 var last = Date.now();
 
-var interval = setInterval(function checkSleep() {
+var interval = timers.setInterval(function checkSleep() {
   var now = Date.now();
   var expected = last + frequency;
   last = now;
diff --git a/src/sleep.js b/src/sleep.js
index fcc3ce7..b7de92f 100644
--- a/src/sleep.js
+++ b/src/sleep.js
@@ -3,13 +3,14 @@
 // it's coming back from sleep.
 
 const EventEmitter = require('./EventEmitter');
+const timers = require('timers');
 
 const sleep = new EventEmitter();
 const frequency = 60 * 1000; // check for sleep once a minute
 const fudge = 5 * 1000;
 let last = Date.now();
 
-const interval = setInterval(function checkSleep() {
+const interval = timers.setInterval(function checkSleep() {
   const now = Date.now();
   const expected = last + frequency;
   last = now;