diff --git a/Build/MQTTnet.nuspec b/Build/MQTTnet.nuspec
index 7ddd3e9..f0e4c3d 100644
--- a/Build/MQTTnet.nuspec
+++ b/Build/MQTTnet.nuspec
@@ -25,7 +25,7 @@
 * [Server] The subscription interceptor now supports altering the entire topic filter.
 * [Server] Exposed more properties to the connection validator context.
 * [MQTTnet.Server] Added authentication support via Python script file.
-* [MQTTnet.Server] Migrated the result of connection validations to _ReasonCode_ (MQTTv5) instead of _ReturnCode_ (MQTTv3 only).
+* [MQTTnet.Server] Migrated the result of connection validations to _ReasonCode_ (MQTTv5) instead of _ReturnCode_ (MQTTv3 only) (BREAKING CHANGE!).
     </releaseNotes>
     <copyright>Copyright Christian Kratky 2016-2019</copyright>
     <tags>MQTT Message Queue Telemetry Transport MQTTClient MQTTServer Server MQTTBroker Broker NETStandard IoT InternetOfThings Messaging Hardware Arduino Sensor Actuator M2M ESP Smart Home Cities Automation Xamarin</tags>