diff --git a/game-lib.js b/game-lib.js
index e7ffdbd..2069b65 100644
--- a/game-lib.js
+++ b/game-lib.js
@@ -685,7 +685,7 @@ GameLib.D3.Material = function(
     this.alphaTest = alphaTest;
 
     if (typeof clippingPlanes == 'undefined') {
-        clippingPlanes = null;
+        clippingPlanes = [];
     }
     this.clippingPlanes = clippingPlanes;