diff --git a/phpBB/includes/mcp/mcp_notes.php b/phpBB/includes/mcp/mcp_notes.php
index d3a4ee4e98..72e03c00f2 100644
--- a/phpBB/includes/mcp/mcp_notes.php
+++ b/phpBB/includes/mcp/mcp_notes.php
@@ -98,7 +98,7 @@ class mcp_notes
 		$userrow = $db->sql_fetchrow($result);
 		$db->sql_freeresult($result);
 
-		if (!$userrow)
+		if (!$userrow || (int) $userrow['user_id'] === ANONYMOUS)
 		{
 			trigger_error('NO_USER');
 		}
diff --git a/phpBB/includes/mcp/mcp_warn.php b/phpBB/includes/mcp/mcp_warn.php
index 0ad4b8bdfd..f487cc5a39 100644
--- a/phpBB/includes/mcp/mcp_warn.php
+++ b/phpBB/includes/mcp/mcp_warn.php
@@ -390,7 +390,7 @@ class mcp_warn
 		$user_row = $db->sql_fetchrow($result);
 		$db->sql_freeresult($result);
 
-		if (!$user_row)
+		if (!$user_row || (int) $user_row['user_id'] === ANONYMOUS)
 		{
 			trigger_error('NO_USER');
 		}