diff --git a/src/main/java/com/university/chat/Server/UserManager.java b/src/main/java/com/university/chat/Server/UserManager.java
index 07cbc2d..5ab7ec7 100644
--- a/src/main/java/com/university/chat/Server/UserManager.java
+++ b/src/main/java/com/university/chat/Server/UserManager.java
@@ -19,7 +19,7 @@ public class UserManager {
     }
 
     public String listUsers() {
-        return users.keySet().toString();
+        return String.join(",", users.keySet());
     }
 
     public Iterable<ClientSession> getAllSessions() {