diff --git a/core/js/js.js b/core/js/js.js
index f2cdf7c93e..3651635541 100644
--- a/core/js/js.js
+++ b/core/js/js.js
@@ -1670,21 +1670,26 @@ OC.Util = {
 
 	/**
 	 * Returns a file size in bytes from a humanly readable string
+	 * Makes 2kB to 2048.
+	 * Inspired by computerFileSize in helper.php
 	 * @param  {string} string file size in human readable format
 	 * @return {number} or null if string could not be parsed
 	 *
-	 * Makes 2kB to 2048.
 	 *
-	 * Inspired by computerFileSize in helper.php
 	 */
 	computerFileSize: function (string) {
-		var s = string.toLowerCase();
-
-		if (!isNaN(parseFloat(s)) && isFinite(s)) {
-			return parseFloat(s);
+		if (typeof string != 'string') {
+			return null;
 		}
 
-		var bytes_array = {
+		var s = string.toLowerCase();
+		var bytes = parseFloat(s)
+
+		if (!isNaN(bytes) && isFinite(s)) {
+			return bytes;
+		}
+
+		var bytesArray = {
 			'b' : 1,
 			'k' : 1024,
 			'kb': 1024,
@@ -1698,13 +1703,10 @@ OC.Util = {
 			'p' : 1024 * 1024 * 1024 * 1024 * 1024
 		};
 
-		var bytes = parseFloat(s);
-
 		var matches = s.match(/([kmgtp]?b?)$/i);
 		if (matches[1]) {
-			bytes = bytes * bytes_array[matches[1]];
-		}
-		else {
+			bytes = bytes * bytesArray[matches[1]];
+		} else {
 			return null;
 		}
 
diff --git a/core/js/tests/specs/coreSpec.js b/core/js/tests/specs/coreSpec.js
index 39060f4e47..370ebc6ba2 100644
--- a/core/js/tests/specs/coreSpec.js
+++ b/core/js/tests/specs/coreSpec.js
@@ -593,6 +593,8 @@ describe('Core base tests', function() {
 		describe('computerFileSize', function() {
 			it('correctly parses file sizes from a human readable formated string', function() {
 				var data = [
+					['125', 125],
+					['125.25', 125.25],
 					['0 B', 0],
 					['125 B', 125],
 					['125b', 125],
@@ -603,13 +605,20 @@ describe('Core base tests', function() {
 					['119.2 GB', 127990025421],
 					['119.2gb', 127990025421],
 					['116.4 TB', 127983153473126],
-					['116.4tb', 127983153473126],
-					['foobar', null]
+					['116.4tb', 127983153473126]
 				];
 				for (var i = 0; i < data.length; i++) {
 					expect(OC.Util.computerFileSize(data[i][0])).toEqual(data[i][1]);
 				}
 			});
+			it('returns null if the parameter is not a string', function() {
+				expect(OC.Util.computerFileSize(NaN)).toEqual(null);
+				expect(OC.Util.computerFileSize(125)).toEqual(null);
+			});
+			it('returns null if the string is unparsable', function() {
+				expect(OC.Util.computerFileSize('')).toEqual(null);
+				expect(OC.Util.computerFileSize('foobar')).toEqual(null);
+			});
 		});
 		describe('stripTime', function() {
 			it('strips time from dates', function() {