diff --git a/src/client/MapleCharacter.java b/src/client/MapleCharacter.java
index 1181238342..3774409a04 100644
--- a/src/client/MapleCharacter.java
+++ b/src/client/MapleCharacter.java
@@ -167,6 +167,7 @@ import server.life.MobSkillFactory;
 import server.maps.MapleMapItem;
 import net.server.audit.locks.MonitoredLockType;
 import net.server.audit.locks.factory.MonitoredReentrantLockFactory;
+import org.apache.mina.util.ConcurrentHashSet;
 
 public class MapleCharacter extends AbstractMapleCharacterObject {
     private static final MapleItemInformationProvider ii = MapleItemInformationProvider.getInstance();
@@ -250,7 +251,7 @@ public class MapleCharacter extends AbstractMapleCharacterObject {
     private final Map<Short, MapleQuestStatus> quests;
     private Set<MapleMonster> controlled = new LinkedHashSet<>();
     private Map<Integer, String> entered = new LinkedHashMap<>();
-    private Set<MapleMapObject> visibleMapObjects = new LinkedHashSet<>();
+    private Set<MapleMapObject> visibleMapObjects = new ConcurrentHashSet<>();
     private Map<Skill, SkillEntry> skills = new LinkedHashMap<>();
     private Map<Integer, Integer> activeCoupons = new LinkedHashMap<>();
     private Map<Integer, Integer> activeCouponRates = new LinkedHashMap<>();
@@ -8616,8 +8617,9 @@ public class MapleCharacter extends AbstractMapleCharacterObject {
                 }
             }
         };
-        
-        map.registerCharacterStatUpdate(r);
+        if (map != null) {
+            map.registerCharacterStatUpdate(r);
+	}
     }
     
     private Pair<MapleStat, Integer> calcHpRatioUpdate(int newHp, int oldHp) {