diff --git a/README.md b/README.md
index b23be1891..cee2870df 100644
--- a/README.md
+++ b/README.md
@@ -373,6 +373,7 @@ You can read all about the philosophy behind Lazer [here](http://phaser.io/news/
 * Sound.play when using an AudioTag would ignore the muted state of the SoundManager and play regardless. It now checks the SoundManager.mute state on play, and sets the volume accorindingly (thanks @brianbunch #2139)
 * Graphics objects can now have a Physics Body directly attached to them, where-as before it would throw an error due to a lack of anchor property (thanks @NLilley #2400)
 * A Game Object with `fixedToCamera = true` that was then set for Input, and enabled for dragging from its center (`input.enableDrag(true)`) would throw an error upon being dragged (thanks @solusipse #2367)
+* P2.World.updateBoundsCollisionGroup wouldn't use the `boundsCollisionGroup` mask if you passed `true` as the argument, only if it was left undefined.
 
 ### Pixi Updates
 
diff --git a/src/physics/p2/World.js b/src/physics/p2/World.js
index 450942618..753e69a97 100644
--- a/src/physics/p2/World.js
+++ b/src/physics/p2/World.js
@@ -615,9 +615,9 @@ Phaser.Physics.P2.prototype = {
     */
     updateBoundsCollisionGroup: function (setCollisionGroup) {
 
-        var mask = this.everythingCollisionGroup.mask;
+        if (setCollisionGroup === undefined) { setCollisionGroup = true; }
 
-        if (setCollisionGroup === undefined) { mask = this.boundsCollisionGroup.mask; }
+        var mask = (setCollisionGroup) ? this.boundsCollisionGroup.mask : this.everythingCollisionGroup.mask;
 
         if (this.walls.left)
         {