diff --git a/gradle/libs.versions.toml b/gradle/libs.versions.toml
index 8a00ba7..fb9c150 100644
--- a/gradle/libs.versions.toml
+++ b/gradle/libs.versions.toml
@@ -1,12 +1,12 @@
 [versions]
-awaitility = "4.2.1"
+awaitility = "4.3.0"
 checkstyle = "10.12.5"
 jackson = "2.17.2"
 jacoco = "0.8.12"
-junit = "5.10.2"
-junit-platform = "1.10.2"
-spotbugs = "6.0.12"
-spotbugs-annotations = "4.8.6"
+junit = "6.1.0"
+junit-platform = "6.1.0"
+spotbugs = "6.5.6"
+spotbugs-annotations = "4.10.2"
 spotless = "6.25.0"
 
 [libraries]
diff --git a/src/main/java/dev/krotname/networkchat/network/ChatHistoryStore.java b/src/main/java/dev/krotname/networkchat/network/ChatHistoryStore.java
index c8afa1a..e13e576 100644
--- a/src/main/java/dev/krotname/networkchat/network/ChatHistoryStore.java
+++ b/src/main/java/dev/krotname/networkchat/network/ChatHistoryStore.java
@@ -24,6 +24,7 @@ public final class ChatHistoryStore {
   private final Path historyFile;
   private final int historyLimit;
   private final List<ChatMessage> messages = new ArrayList<>();
+  private final Object lock = new Object();
   private final boolean enabled;
   private int corruptRecordCount;
 
@@ -45,41 +46,49 @@ public static ChatHistoryStore open(Path historyFile, int historyLimit) {
     return new ChatHistoryStore(historyFile, historyLimit, true);
   }
 
-  public synchronized void save(ChatMessage message) {
-    if (!enabled || !isPersistable(message)) {
-      return;
+  public void save(ChatMessage message) {
+    synchronized (lock) {
+      if (!enabled || !isPersistable(message)) {
+        return;
+      }
+      messages.add(message);
+      trimToLimit();
+      rewrite();
     }
-    messages.add(message);
-    trimToLimit();
-    rewrite();
   }
 
-  public synchronized List<ChatMessage> recentRoomMessages(String roomName, int limit) {
-    if (limit <= 0) {
-      return List.of();
-    }
-    List<ChatMessage> roomMessages = new ArrayList<>();
-    for (ChatMessage message : messages) {
-      if (message.type() == MessageType.ROOM_TEXT && roomName.equals(message.room())) {
-        roomMessages.add(message);
+  public List<ChatMessage> recentRoomMessages(String roomName, int limit) {
+    synchronized (lock) {
+      if (limit <= 0) {
+        return List.of();
       }
+      List<ChatMessage> roomMessages = new ArrayList<>();
+      for (ChatMessage message : messages) {
+        if (message.type() == MessageType.ROOM_TEXT && roomName.equals(message.room())) {
+          roomMessages.add(message);
+        }
+      }
+      return last(roomMessages, limit);
     }
-    return last(roomMessages, limit);
   }
 
-  public synchronized Set<String> knownRooms() {
-    Set<String> rooms = new TreeSet<>();
-    rooms.add(ChatMessage.GENERAL_ROOM);
-    for (ChatMessage message : messages) {
-      if (message.room() != null && !message.room().isBlank()) {
-        rooms.add(message.room());
+  public Set<String> knownRooms() {
+    synchronized (lock) {
+      Set<String> rooms = new TreeSet<>();
+      rooms.add(ChatMessage.GENERAL_ROOM);
+      for (ChatMessage message : messages) {
+        if (message.room() != null && !message.room().isBlank()) {
+          rooms.add(message.room());
+        }
       }
+      return Collections.unmodifiableSet(rooms);
     }
-    return Collections.unmodifiableSet(rooms);
   }
 
-  public synchronized int corruptRecordCount() {
-    return corruptRecordCount;
+  public int corruptRecordCount() {
+    synchronized (lock) {
+      return corruptRecordCount;
+    }
   }
 
   private void load() {