diff --git a/lib/core/src/lib/viewer/components/viewer-render.component.ts b/lib/core/src/lib/viewer/components/viewer-render.component.ts
index 19bc11c446..e77009942b 100644
--- a/lib/core/src/lib/viewer/components/viewer-render.component.ts
+++ b/lib/core/src/lib/viewer/components/viewer-render.component.ts
@@ -165,7 +165,7 @@ export class ViewerRenderComponent implements OnChanges, OnInit, OnDestroy {
         this.extension = this.viewUtilService.getFileExtension(this.internalFileName);
         this.internalViewerType = this.viewerType === 'unknown' ? this.viewUtilService.getViewerType(this.extension, this.mimeType) : this.viewerType;
 
-        this.extensionChange.emit(this.internalViewerType);
+        this.extensionChange.emit(this.extension);
         this.scrollTop();
     }