diff --git a/app/ModelSerializers/AdminMemberSerializer.php b/app/ModelSerializers/AdminMemberSerializer.php
index 9bbb5ff3..21d6aa47 100644
--- a/app/ModelSerializers/AdminMemberSerializer.php
+++ b/app/ModelSerializers/AdminMemberSerializer.php
@@ -20,5 +20,6 @@ final class AdminMemberSerializer extends AbstractMemberSerializer
 {
     protected static $array_mappings = [
         'Email' => 'email:json_string',
+        'UserExternalId' => 'user_external_id:json_int'
     ];
 }
\ No newline at end of file