diff --git a/plupload.js b/plupload.js
index f8be4d1..f03659b 100644
--- a/plupload.js
+++ b/plupload.js
@@ -60,8 +60,14 @@ Drupal.behaviors.plupload = {
 
         // Only allow the submit to proceed if there are files and they've all
         // completed uploading.
-        // @todo Implement a setting for whether the field is required, rather
-        //   than assuming that all are.
+
+        if (uploader.files.length == 0 && !pluploadSettings.required) {
+          for (var attr in originalFormAttributes) {
+            $form.attr(attr, originalFormAttributes[attr]);
+          }
+          return;
+        }
+
         if (uploader.files.length > 0 && uploader.total.uploaded == uploader.files.length) {
           // Plupload's html4 runtime has a bug where it changes the attributes
           // of the form to handle the file upload, but then fails to change
diff --git a/plupload.module b/plupload.module
index 9d55695..57d71b0 100644
--- a/plupload.module
+++ b/plupload.module
@@ -220,6 +220,8 @@ function plupload_element_pre_render($element) {
     );
   }
 
+  $settings['required'] = $element['#required'];
+
   if (empty($element['#description'])) {
     $element['#description'] = '';
   }