diff --git a/examples/wms-custom-proj.js b/examples/wms-custom-proj.js
index 39ba860d2b..8463e8c49a 100644
--- a/examples/wms-custom-proj.js
+++ b/examples/wms-custom-proj.js
@@ -8,10 +8,15 @@ goog.require('ol.proj');
 goog.require('ol.source.TileWMS');
 
 
-var projection = ol.proj.configureProj4jsProjection({
+var proj4Proj = new proj4.Proj('EPSG:21781');
+var projection = ol.proj.addProjection({
   code: 'EPSG:21781',
-  extent: [485869.5728, 76443.1884, 837076.5648, 299941.7864]
+  extent: [485869.5728, 76443.1884, 837076.5648, 299941.7864],
+  units: proj4Proj.units
 });
+// The transform is needed for the ScaleLine control. Otherwise this example
+// would also work without proj4js.
+ol.proj.addCoordinateTransforms('EPSG:4326', projection, proj4(proj4Proj));
 
 var extent = [420000, 30000, 900000, 350000];
 var layers = [