diff --git a/src/socket/socketuser.js b/src/socket/socketuser.js
index 28efb8b..b63392d 100644
--- a/src/socket/socketuser.js
+++ b/src/socket/socketuser.js
@@ -174,7 +174,9 @@ export class SocketUser {
       data.objectType,
       data.filter
     );
-    callback({ success: true });
+    if (typeof callback === 'function') {
+      callback({ success: true });
+    }
   }
 
   async handleSubscribeToObjectUpdateEvent(data, callback) {
@@ -182,7 +184,9 @@ export class SocketUser {
       data._id,
       data.objectType
     );
-    callback(result);
+    if (typeof callback === 'function') {
+      callback(result);
+    }
   }
 
   async handleSubscribeToObjectEventEvent(data) {