diff --git a/src/helpers/BoxHelper.js b/src/helpers/BoxHelper.js
index 312a7aa621fd24..cd951f49e52ef8 100644
--- a/src/helpers/BoxHelper.js
+++ b/src/helpers/BoxHelper.js
@@ -93,7 +93,7 @@ class BoxHelper extends LineSegments {
 
 	copy( source ) {
 
-		LineSegments.prototype.copy.call( this, source );
+		super.copy( source );
 
 		this.object = source.object;