diff --git a/modules/file/file.js b/modules/file/file.js
index 0135a3b..89baffa 100644
--- a/modules/file/file.js
+++ b/modules/file/file.js
@@ -64,6 +64,9 @@ Drupal.file = Drupal.file || {
    * Client-side file input validation of file extensions.
    */
   validateExtension: function (event) {
+    if (!this.value) {
+      return false;
+    }
     // Remove any previous errors.
     $('.file-upload-js-error').remove();