diff --git a/api/js/etemplate/et2_widget_vfs.js b/api/js/etemplate/et2_widget_vfs.js
index aa92e9c22a..999a9c93cd 100644
--- a/api/js/etemplate/et2_widget_vfs.js
+++ b/api/js/etemplate/et2_widget_vfs.js
@@ -947,7 +947,7 @@ var et2_vfsUpload = /** @class */ (function (_super) {
         if (file_data && (typeof file_data.download_url != 'undefined')) {
             var fe_mime = egw_get_file_editor_prefered_mimes(file_data.mime);
             // Check if the link entry is mime with media type, in order to open it in expose view
-            if (typeof file_data.mime != 'undefined' &&
+            if (typeof file_data.mime === 'string' &&
                 (file_data.mime.match(mime.mime_regexp, 'ig') || (fe_mime && fe_mime.mime[file_data.mime]))) {
                 vfs_attrs.onclick = function (ev) {
                     ev.stopPropagation();
diff --git a/api/js/etemplate/et2_widget_vfs.ts b/api/js/etemplate/et2_widget_vfs.ts
index 3745080d56..347979c6af 100644
--- a/api/js/etemplate/et2_widget_vfs.ts
+++ b/api/js/etemplate/et2_widget_vfs.ts
@@ -1092,7 +1092,7 @@ class et2_vfsUpload extends et2_file
 		{
 			var fe_mime = egw_get_file_editor_prefered_mimes(file_data.mime);
 			// Check if the link entry is mime with media type, in order to open it in expose view
-			if (typeof file_data.mime != 'undefined' &&
+			if (typeof file_data.mime === 'string' &&
 				(file_data.mime.match(mime.mime_regexp,'ig') || (fe_mime && fe_mime.mime[file_data.mime])))
 			{
 				vfs_attrs.onclick = function(ev) {