diff --git a/Sources/User.php b/Sources/User.php
index e95ad182e8..24ac2595a2 100644
--- a/Sources/User.php
+++ b/Sources/User.php
@@ -2182,7 +2182,11 @@ public function enforceBans(bool $force_check = false, bool $post_kick = false,
 				$_GET['action'] = '';
 				$_GET['board'] = '';
 				$_GET['topic'] = '';
-				unset(Topic::$topic_id, Topic::$info, Board::$board_id, Board::$info);
+				// These are static, so they have to be cleared, not unset.
+				Topic::$topic_id = null;
+				Topic::$info = null;
+				Board::$board_id = null;
+				Board::$info = null;
 
 				$this->logOnline(true);
 			}