diff --git a/src/util/Numerical.js b/src/util/Numerical.js
index 2958ae57..8ccf77f0 100644
--- a/src/util/Numerical.js
+++ b/src/util/Numerical.js
@@ -74,7 +74,7 @@ var Numerical = new function() {
 		 * Numerical.EPSILON.
 		 */
 		isZero: function(val) {
-			return Math.abs(val) <= this.EPSILON;
+			return abs(val) <= this.EPSILON;
 		},
 
 		/**