diff --git a/dist/ol-ext.js b/dist/ol-ext.js
index e6f8d098..8ead948b 100644
--- a/dist/ol-ext.js
+++ b/dist/ol-ext.js
@@ -1,7 +1,7 @@
 /**
  * ol-ext - A set of cool extensions for OpenLayers (ol) in node modules structure
  * @description ol3,openlayers,popup,menu,symbol,renderer,filter,canvas,interaction,split,statistic,charts,pie,LayerSwitcher,toolbar,animation
- * @version v4.0.20
+ * @version v4.0.21
  * @author Jean-Marc Viglino
  * @see https://github.com/Viglino/ol-ext#,
  * @license BSD-3-Clause
diff --git a/dist/ol-ext.min.js b/dist/ol-ext.min.js
index 6507a6aa..51ec35d3 100644
--- a/dist/ol-ext.min.js
+++ b/dist/ol-ext.min.js
@@ -1,7 +1,7 @@
 /**
  * ol-ext - A set of cool extensions for OpenLayers (ol) in node modules structure
  * @description ol3,openlayers,popup,menu,symbol,renderer,filter,canvas,interaction,split,statistic,charts,pie,LayerSwitcher,toolbar,animation
- * @version v4.0.20
+ * @version v4.0.21
  * @author Jean-Marc Viglino
  * @see https://github.com/Viglino/ol-ext#,
  * @license BSD-3-Clause
diff --git a/package.json b/package.json
index 39096523..e211f5fd 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "ol-ext",
-  "version": "4.0.20",
+  "version": "4.0.21",
   "description": "A set of cool extensions for OpenLayers (ol) in node modules structure",
   "main": "dist/ol-ext.js",
   "style": "dist/ol-ext.css",
diff --git a/src/control/FeatureList.js b/src/control/FeatureList.js
index 67e8b18a..433cc15d 100644
--- a/src/control/FeatureList.js
+++ b/src/control/FeatureList.js
@@ -1,6 +1,6 @@
-import ol_geom_Geometry from 'ol/geom/Geometry'
-import ol_control_Control from 'ol/control/Control'
-import ol_ext_element from '../util/element';
+import ol_geom_Geometry from 'ol/geom/Geometry.js'
+import ol_control_Control from 'ol/control/Control.js'
+import ol_ext_element from '../util/element.js';
 
 /** Feature list control
  *
diff --git a/src/control/LayerSwitcher.js b/src/control/LayerSwitcher.js
index 60e91b9c..89bfe827 100644
--- a/src/control/LayerSwitcher.js
+++ b/src/control/LayerSwitcher.js
@@ -8,7 +8,7 @@ import ol_layer_Tile from 'ol/layer/Tile.js'
 import ol_layer_Vector from 'ol/layer/Vector.js'
 import ol_layer_VectorTile from 'ol/layer/VectorTile.js'
 // ol < 6 compatibility VectorImage is not defined
-// import ol_layer_VectorImage from 'ol/layer/VectorImage'
+// import ol_layer_VectorImage from 'ol/layer/VectorImage.js'
 import ol_layer_Image from 'ol/layer/Image.js'
 import ol_layer_Heatmap from 'ol/layer/Heatmap.js'
 import {intersects as ol_extent_intersects} from 'ol/extent.js'
diff --git a/src/interaction/Transform.js b/src/interaction/Transform.js
index 05f1efbf..4f0e9433 100644
--- a/src/interaction/Transform.js
+++ b/src/interaction/Transform.js
@@ -12,7 +12,7 @@ import {fromExtent as ol_geom_Polygon_fromExtent} from 'ol/geom/Polygon.js'
 import {boundingExtent as ol_extent_boundingExtent, buffer as ol_extent_buffer, createEmpty as ol_extent_createEmpty, extend as ol_extent_extend, getCenter as ol_extent_getCenter} from 'ol/extent.js'
 import {unByKey as ol_Observable_unByKey} from 'ol/Observable.js'
 import ol_geom_Polygon from 'ol/geom/Polygon.js'
-import ol_ext_element from '../util/element'
+import ol_ext_element from '../util/element.js'
 
 /** Interaction rotate
  * @constructor
diff --git a/src/layer/Geoportail.js b/src/layer/Geoportail.js
index 22cf6ef1..51cd6e73 100644
--- a/src/layer/Geoportail.js
+++ b/src/layer/Geoportail.js
@@ -6,7 +6,7 @@ import ol_layer_Tile from 'ol/layer/Tile.js'
 import ol_format_WMTSCapabilities from 'ol/format/WMTSCapabilities.js'
 import ol_ext_Ajax from '../util/Ajax.js'
 import {transformExtent as ol_proj_transformExtent} from 'ol/proj.js'
-// import {intersects as ol_extent_intersects} from 'ol/extent'
+// import {intersects as ol_extent_intersects} from 'ol/extent.js'
 
 import ol_source_Geoportail from '../source/Geoportail.js'
 
diff --git a/src/render/Cspline.js b/src/render/Cspline.js
index 7d7a8d11..2fe741fe 100644
--- a/src/render/Cspline.js
+++ b/src/render/Cspline.js
@@ -172,6 +172,6 @@ ol_geom_LineString.prototype.calcCSpline_ = function(options) {
 }
 
 // To use this module with ol/geom/Geometry
-// import 'ol-ext/utils/cspline'
+// import 'ol-ext/utils/cspline.js'
 
 export default ol_coordinate_cspline