diff --git a/src/extras/curves/CatmullRomCurve3.js b/src/extras/curves/CatmullRomCurve3.js
index 9f5cc8c0defc743e8c71ad99182a9d3d712ca038..a2340c4b68a7542889069452d39b3ddbe717fe6d 100644
--- a/src/extras/curves/CatmullRomCurve3.js
+++ b/src/extras/curves/CatmullRomCurve3.js
@@ -191,6 +191,8 @@ CatmullRomCurve3.prototype.copy = function ( source ) {
 
 	Curve.prototype.copy.call( this, source );
 
+	this.points = [];
+
 	for ( var i = 0, l = source.points.length; i < l; i ++ ) {
 
 		var point = source.points[ i ];
diff --git a/src/extras/curves/SplineCurve.js b/src/extras/curves/SplineCurve.js
index 180a7c6216791ea6aadcd7a6f8e121ed2fb4df88..e2e5991be2f6df71a2b824733540ef24415f3ca6 100644
--- a/src/extras/curves/SplineCurve.js
+++ b/src/extras/curves/SplineCurve.js
@@ -46,6 +46,8 @@ SplineCurve.prototype.copy = function ( source ) {
 
 	Curve.prototype.copy.call( this, source );
 
+	this.points = [];
+
 	for ( var i = 0, l = source.points.length; i < l; i ++ ) {
 
 		var point = source.points[ i ];