2 files changed, 4 insertions, 4 deletions
diff --git a/spark-common/src/main/java/me/lucko/spark/common/tick/AbstractTickHook.java b/spark-common/src/main/java/me/lucko/spark/common/tick/AbstractTickHook.java
index a6e8745..2a31e0d 100644
--- a/spark-common/src/main/java/me/lucko/spark/common/tick/AbstractTickHook.java
+++ b/spark-common/src/main/java/me/lucko/spark/common/tick/AbstractTickHook.java
@@ -20,12 +20,12 @@
 
 package me.lucko.spark.common.tick;
 
-import java.util.HashSet;
 import java.util.Set;
+import java.util.concurrent.CopyOnWriteArraySet;
 
 public abstract class AbstractTickHook implements TickHook {
 
-    private final Set<Callback> tasks = new HashSet<>();
+    private final Set<Callback> tasks = new CopyOnWriteArraySet<>();
     private int tick = 0;
 
     protected void onTick() {
diff --git a/spark-common/src/main/java/me/lucko/spark/common/tick/AbstractTickReporter.java b/spark-common/src/main/java/me/lucko/spark/common/tick/AbstractTickReporter.java
index 74a814d..431a641 100644
--- a/spark-common/src/main/java/me/lucko/spark/common/tick/AbstractTickReporter.java
+++ b/spark-common/src/main/java/me/lucko/spark/common/tick/AbstractTickReporter.java
@@ -20,11 +20,11 @@
 
 package me.lucko.spark.common.tick;
 
-import java.util.HashSet;
 import java.util.Set;
+import java.util.concurrent.CopyOnWriteArraySet;
 
 public abstract class AbstractTickReporter implements TickReporter {
-    private final Set<Callback> tasks = new HashSet<>();
+    private final Set<Callback> tasks = new CopyOnWriteArraySet<>();
 
     protected void onTick(double duration) {
         for (Callback r : this.tasks) {