diff --git a/app.js b/app.js
index 66c4be8..49f40dd 100644
--- a/app.js
+++ b/app.js
@@ -160,7 +160,7 @@ peers.on('connection', async socket => {
     producer.on('transportclose', () => {
       console.log('transport for this producer closed ')
       producer.close()
-      router[callId] = null
+      delete router[callId]
     })
 
     // Send back to the client the Producer's id
@@ -191,7 +191,7 @@ peers.on('connection', async socket => {
 
         consumer.on('transportclose', () => {
           console.log('transport close from consumer', callId)
-          router[callId] = null
+          delete router[callId]
         })
 
         consumer.on('producerclose', () => {