diff --git a/lib/battery.js b/lib/battery.js
index 5660ca2..2c514b3 100644
--- a/lib/battery.js
+++ b/lib/battery.js
@@ -100,7 +100,7 @@ module.exports = function (callback) {
         exec('ioreg -n AppleSmartBattery -r | egrep "CycleCount|IsCharging|MaxCapacity|CurrentCapacity";pmset -g batt | grep %', function (error, stdout) {
           let lines = stdout.toString().replace(/ +/g, '').replace(/"+/g, '').replace(/-/g, '').split('\n');
           result.cyclecount = parseInt('0' + util.getValue(lines,'cyclecount', '='), 10);
-          result.ischarging = util.getValue(lines,'ischarging', '=').toLowerCase === 'yes';
+          result.ischarging = util.getValue(lines,'ischarging', '=').toLowerCase() === 'yes';
           result.maxcapacity = parseInt('0' + util.getValue(lines,'maxcapacity', '='), 10);
           result.currentcapacity = parseInt('0' + util.getValue(lines,'currentcapacity', '='), 10);
           let percent = -1;