diff --git a/src/Projector.js b/src/Projector.js
index 4da730f..7c73270 100644
--- a/src/Projector.js
+++ b/src/Projector.js
@@ -97,7 +97,7 @@ Phaser.Plugin.Isometric.Projector.prototype = {
      * @method Phaser.Plugin.Isometric.Projector#unproject
      * @param {Phaser.Plugin.Isometric.Point} point - The Point to project from.
      * @param {Phaser.Point3} out - The Point3 to project to.
-     * @param {number} z - Specified z-plane to project to.
+     * @param {number} [z] - Specified z-plane to project to.
      * @return {Phaser.Point3} The transformed Point3.
      */
     unproject: function (point, out, z) {
@@ -105,6 +105,9 @@ Phaser.Plugin.Isometric.Projector.prototype = {
             out = new Phaser.Point3();
         }
 
+        z = z || 0;
+
+
         var x = point.x - (this.game.world.width * this.anchor.x);
         var y = point.y - (this.game.world.height * this.anchor.y) + z;