diff --git a/invite.module b/invite.module
index 899bb2a..6966bdc 100644
--- a/invite.module
+++ b/invite.module
@@ -1405,7 +1405,7 @@ function _invite_filter_invited_emails($emails) {
  *   error.
  */
 function _invite_filter_registered_emails($emails) {
-  if (!is_array($emails)) {
+  if (!is_array($emails) || count($emails) == 0) {
     return NULL;
   }