diff --git a/arcball.js b/arcball.js
index c5330ad..4f57c05 100644
--- a/arcball.js
+++ b/arcball.js
@@ -90,7 +90,7 @@ ArcballCamera.prototype.updateCameraMatrix = function() {
 }
 
 ArcballCamera.prototype.eyePos = function() {
-    return [camera.invCamera[12], camera.invCamera[13], camera.invCamera[14]];
+    return [this.invCamera[12], this.invCamera[13], this.invCamera[14]];
 }
 
 ArcballCamera.prototype.eyeDir = function() {