diff --git a/htudemo.js b/htudemo.js
index 7fb1d06..90b8132 100644
--- a/htudemo.js
+++ b/htudemo.js
@@ -7,10 +7,10 @@ var i2c_htu21d = require('./index.js');
 // For example: i2c_htu21d({device: '/dev/i2c-1'});
 var htu21df = new i2c_htu21d();
 
-htu21df.readTemperature(function (temp) {
+htu21df.readTemperature(function (err, temp) {
     console.log('Temperature, C:', temp);
 
-    htu21df.readHumidity(function (humidity) {
+    htu21df.readHumidity(function (err, humidity) {
         console.log('Humidity, RH %:', humidity);
     });
 });
diff --git a/htutest.js b/htutest.js
index 8d75a87..bc5bb63 100644
--- a/htutest.js
+++ b/htutest.js
@@ -7,10 +7,10 @@ var i2c_htu21d = require('./index.js');
 // For example: i2c_htu21d({device: '/dev/i2c-1/'});
 var htu21df = new i2c_htu21d();
 
-htu21df.readTemperature(function (temp) {
+htu21df.readTemperature(function (err, temp) {
     console.log('Temperature, C:', temp);
 
-    htu21df.readHumidity(function (humidity) {
+     htu21df.readHumidity(function (err, humidity) {
         console.log('Humidity, RH %:', humidity);
 
         console.log('new i2c_htu21d({});');
diff --git a/index.js b/index.js
index 79c1133..f957055 100644
--- a/index.js
+++ b/index.js
@@ -67,12 +67,10 @@ var htu21d = function (i2copts_arg) {
 
 htu21d.prototype.readTemperature = function(callback) {
     var that = this;
-    this.i2c.writeByte(HTU21D_READTEMP_NH, function(err) {
-        if (err) {
-            console.log(err);
-            return err;
-        }
-        else {
+  this.i2c.writeByte(HTU21D_READTEMP_NH, function(err, data) {
+    if (err) {
+      return callback(err, null);
+    } else {
             setTimeout(function() {
                 that.i2c.read(3, function(err, data) {
                     if (err) {
@@ -83,7 +81,7 @@ htu21d.prototype.readTemperature = function(callback) {
                             var rawtemp = ((data[0] << 8) | data[1]) & 0xFFFC;
                             var temperature = ((rawtemp / 65536.0) * 175.72) - 46.85;
                             //console.log("Temperature, C:", temperature.toFixed(1));
-                            callback(temperature.toFixed(1));
+                            callback(null, temperature.toFixed(1));
                         }
                     }
                 });
@@ -96,8 +94,7 @@ htu21d.prototype.readHumidity = function(callback) {
     var that = this;
     this.i2c.writeByte(HTU21D_READHUMI_NH, function(err) {
         if (err) {
-            console.log(err);
-            return err;
+         return callback(err, null);
         }
         else {
             setTimeout(function() {
@@ -110,7 +107,7 @@ htu21d.prototype.readHumidity = function(callback) {
                             var rawhumi = ((data[0] << 8) | data[1]) & 0xFFFC;
                             var humidity = ((rawhumi / 65536.0) * 125.0) - 6.0;
                             //console.log("Relative Humidity, %:", humidity);
-                            callback(humidity.toFixed(1));
+                            callback(null, humidity.toFixed(1));
                         }
                     }
                 });