diff --git a/src/renderers/webgl/WebGLRenderLists.js b/src/renderers/webgl/WebGLRenderLists.js
index 479ec11dd0e7ceac1d7c1c5db7deaf88b74e330f..fb2e0972ffcad02dba68c7cc164b4f7c57c6dc27 100644
--- a/src/renderers/webgl/WebGLRenderLists.js
+++ b/src/renderers/webgl/WebGLRenderLists.js
@@ -103,8 +103,8 @@ function WebGLRenderList() {
 
 	function sort() {
 
-		opaque.sort( painterSortStable );
-		transparent.sort( reversePainterSortStable );
+		if ( opaque.length > 1 ) opaque.sort( painterSortStable );
+		if ( transparent.length > 1 ) transparent.sort( reversePainterSortStable );
 
 	}