diff --git a/mod/forum/lib.php b/mod/forum/lib.php
index 7abd4bb..d18ab8a 100644
--- a/mod/forum/lib.php
+++ b/mod/forum/lib.php
@@ -3714,7 +3714,10 @@ function forum_file_area_name($post) {
  *
  */
 function forum_file_area($post) {
-    return make_upload_directory( forum_file_area_name($post) );
+    $path = forum_file_area_name($post);
+    if ($path) {
+      return make_upload_directory($path);
+    }
 }
 
 /**