diff --git a/core/includes/file.inc b/core/includes/file.inc
index 15a1811..8c2e13a 100644
--- a/core/includes/file.inc
+++ b/core/includes/file.inc
@@ -946,15 +946,18 @@ function file_scan_directory($dir, $mask, $options = array(), $depth = 0) {
     $dir_has_slash = (substr($dir, -1) === '/');
   }
 
-  // By default, do not check for files in common special-purpose directories.
-  // The folders here are front-end related and they have been added to avoid
-  // issues with Drupal recursive scanning. In this case, we added node_modules
-  // and bower_components. This also improves performance on frontend builds.
-  $ignore_directories = Settings::get('drupal_file_scan_ignore_directories', [
-    'node_modules',
-    'bower_components',
-  ]);
-  $default_nomask = '/^' . implode('|', $ignore_directories) . '$/';
+  // By default, when there is no explicit 'nomask' option, do not check for
+  // files in common special-purpose directories. The folders here are front-end
+  // related and they have been added to avoid issues with Drupal recursive
+  // scanning. In this case, we added node_modules and bower_components. This
+  // also improves performance on frontend builds.
+  if (!isset($options['nomask'])) {
+    $ignore_directories = Settings::get('drupal_file_scan_ignore_directories', [
+      'node_modules',
+      'bower_components',
+    ]);
+    $options['nomask'] = '/^' . implode('|', $ignore_directories) . '$/';
+  }
 
   $options['key'] = in_array($options['key'], array('uri', 'filename', 'name')) ? $options['key'] : 'uri';
   $files = array();
@@ -964,10 +967,7 @@ function file_scan_directory($dir, $mask, $options = array(), $depth = 0) {
     if ($handle = @opendir($dir)) {
       while (FALSE !== ($filename = readdir($handle))) {
         // Skip this file if it matches the nomask or starts with a dot.
-        if ($filename[0] != '.'
-          && !(isset($options['nomask']) && preg_match($options['nomask'], $filename))
-          && !(!empty($default_nomask) && preg_match($default_nomask, $filename))
-          ) {
+        if ($filename[0] != '.' && !(isset($options['nomask']) && preg_match($options['nomask'], $filename))) {
           if ($depth == 0 && $dir_has_slash) {
             $uri = "$dir$filename";
           }