diff --git a/includes/common.inc b/includes/common.inc
index 6466f1a..3910364 100644
--- a/includes/common.inc
+++ b/includes/common.inc
@@ -5561,8 +5561,9 @@ function drupal_system_listing($mask, $directory, $key = 'name', $min_depth = 1)
     }
   }
 
-  // Always search sites/all/* as well as the global directories.
-  $searchdir[] = 'sites/all/' . $directory;
+  if (file_exists("sites/all/$directory")) {
+    $searchdir[] = "sites/all/$directory";
+  }
 
   if (file_exists("$config/$directory")) {
     $searchdir[] = "$config/$directory";