diff --git a/projects/common-map/src/fm-map/components/feature-thumbnail/feature-thumbnail.component.ts b/projects/common-map/src/fm-map/components/feature-thumbnail/feature-thumbnail.component.ts
index 274e00f..2a2ab15 100644
--- a/projects/common-map/src/fm-map/components/feature-thumbnail/feature-thumbnail.component.ts
+++ b/projects/common-map/src/fm-map/components/feature-thumbnail/feature-thumbnail.component.ts
@@ -59,7 +59,7 @@ export class GeometryThumbnailComponent implements AfterViewInit {
     if(canvas && canvas.nativeElement && geometry && style) {
       let renderContext = render.toContext(canvas.nativeElement.getContext( '2d'),{ size: [width, height] });  
 
-      let geom   = geometry.clone(),
+      let geom   = geometry.clone() as Polygon,
       line   = geom.getCoordinates()[0],
       e = extent.boundingExtent( line );