diff --git a/app/src/Model/Table/IdentifierAssignmentsTable.php b/app/src/Model/Table/IdentifierAssignmentsTable.php
index c1a905c8c..1e8052573 100644
--- a/app/src/Model/Table/IdentifierAssignmentsTable.php
+++ b/app/src/Model/Table/IdentifierAssignmentsTable.php
@@ -158,7 +158,7 @@ public function assign(
     bool   $provision=true,
 // XXX CFM-76 HistoryRecords don't seem to do anything with actorPersonId yet
 //     Also need to update StandardController or something for regular requests
-    int    $actorPersonId=null
+    ?int    $actorPersonId=null
   ): array {
     $ret = [
       'already'   => [],