diff --git a/box2d/box2dweb-test.ts b/box2d/box2dweb-test.ts
index 3d9fc19bd..51dabf178 100644
--- a/box2d/box2dweb-test.ts
+++ b/box2d/box2dweb-test.ts
@@ -12,5 +12,6 @@ import b2Joints = Box2D.Dynamics.Joints;
 var w1 = new Box2D.Dynamics.b2World(new Box2D.Common.Math.b2Vec2(0, 10), true);
 var w2 = new b2Dynamics.b2World(new b2Math.b2Vec2(0, 10), true);
 
-var debugDraw = new Box2D.Dynamics.b2DebugDraw();
-debugDraw.SetSprite(document.getElementsByTagName("canvas")[0].getContext("2d"));
+var debugDraw = new Box2D.Dynamics.b2DebugDraw(),
+    canvasElement = <HTMLCanvasElement>document.getElementsByTagName("canvas")[0];
+debugDraw.SetSprite(canvasElement.getContext("2d"));