diff --git a/src/math/Box3.js b/src/math/Box3.js
index 65947706015157ae3ff9958d49d6cdef4878139c..9086616869cff2b47213806b127e93edab4747b2 100644
--- a/src/math/Box3.js
+++ b/src/math/Box3.js
@@ -262,8 +262,7 @@ Object.assign( Box3.prototype, {
 			_box.copy( geometry.boundingBox );
 			_box.applyMatrix4( object.matrixWorld );
 
-			this.expandByPoint( _box.min );
-			this.expandByPoint( _box.max );
+			this.union( _box );
 
 		}