diff --git a/plugin/src/main/java/lol/pyr/znpcsplus/util/Viewable.java b/plugin/src/main/java/lol/pyr/znpcsplus/util/Viewable.java
index 3b62050..8bd8f56 100644
--- a/plugin/src/main/java/lol/pyr/znpcsplus/util/Viewable.java
+++ b/plugin/src/main/java/lol/pyr/znpcsplus/util/Viewable.java
@@ -3,11 +3,11 @@ package lol.pyr.znpcsplus.util;
 import org.bukkit.entity.Player;
 
 import java.util.Collections;
-import java.util.HashSet;
 import java.util.Set;
+import java.util.concurrent.ConcurrentHashMap;
 
 public abstract class Viewable {
-    private final Set<Player> viewers = new HashSet<>();
+    private final Set<Player> viewers = ConcurrentHashMap.newKeySet();
 
     public void delete() {
         UNSAFE_hideAll();