diff --git a/akka-actor/src/main/scala/akka/dispatch/AbstractDispatcher.scala b/akka-actor/src/main/scala/akka/dispatch/AbstractDispatcher.scala
index 6a2c34657b..be68266a9a 100644
--- a/akka-actor/src/main/scala/akka/dispatch/AbstractDispatcher.scala
+++ b/akka-actor/src/main/scala/akka/dispatch/AbstractDispatcher.scala
@@ -26,7 +26,12 @@ final case class Envelope private (val message: Any, val sender: ActorRef)
 
 object Envelope {
   def apply(message: Any, sender: ActorRef, system: ActorSystem): Envelope = {
-    if (message == null) throw InvalidMessageException("Message is null")
+    if (message == null) {
+      if (sender eq Actor.noSender)
+        throw InvalidMessageException(s"Message is null.")
+      else
+        throw InvalidMessageException(s"Message sent from [$sender] is null.")
+    }
     new Envelope(message, if (sender ne Actor.noSender) sender else system.deadLetters)
   }
 }