diff --git a/.github/workflows/ReleaseNotes.md b/.github/workflows/ReleaseNotes.md
index 7166dbea..2cb50c8f 100644
--- a/.github/workflows/ReleaseNotes.md
+++ b/.github/workflows/ReleaseNotes.md
@@ -1,2 +1,3 @@
 [Core] Fixed a memory leak in _AsyncSignal_ implementation (#1586, thanks to @mario-zelger).
 [Server] Fix not properly reset statistics (#1587, thanks to @damikun).
+[Server] Now using an empty string as the sender client ID for injected application messages (#1583, thanks to @xljiulang).
\ No newline at end of file
diff --git a/Source/MQTTnet/Server/InjectedMqttApplicationMessage.cs b/Source/MQTTnet/Server/InjectedMqttApplicationMessage.cs
index 0190ec00..7d027ab6 100644
--- a/Source/MQTTnet/Server/InjectedMqttApplicationMessage.cs
+++ b/Source/MQTTnet/Server/InjectedMqttApplicationMessage.cs
@@ -3,7 +3,6 @@
 // See the LICENSE file in the project root for more information.
 
 using System;
-using System.Threading;
 
 namespace MQTTnet.Server
 {