diff --git a/akka-actor-tests/src/test/scala/akka/pattern/AskSpec.scala b/akka-actor-tests/src/test/scala/akka/pattern/AskSpec.scala
index 2fac82ab20..8838af1e6b 100644
--- a/akka-actor-tests/src/test/scala/akka/pattern/AskSpec.scala
+++ b/akka-actor-tests/src/test/scala/akka/pattern/AskSpec.scala
@@ -59,7 +59,7 @@ class AskSpec extends AkkaSpec {
       implicit val timeout = Timeout(0 seconds)
       val echo = system.actorOf(Props(new Actor { def receive = { case x ⇒ sender() ! x } }))
       val f = echo ? "foo"
-      val expectedMsg = "Timeout length must not be negative, question not sent to [%s]. Sender[null] sent the message of type \"java.lang.String\"." format echo
+      val expectedMsg = "Timeout length must be positive, question not sent to [%s]. Sender[null] sent the message of type \"java.lang.String\"." format echo
       intercept[IllegalArgumentException] {
         Await.result(f, timeout.duration)
       }.getMessage should ===(expectedMsg)
@@ -69,7 +69,7 @@ class AskSpec extends AkkaSpec {
       implicit val timeout = Timeout(-1000 seconds)
       val echo = system.actorOf(Props(new Actor { def receive = { case x ⇒ sender() ! x } }))
       val f = echo ? "foo"
-      val expectedMsg = "Timeout length must not be negative, question not sent to [%s]. Sender[null] sent the message of type \"java.lang.String\"." format echo
+      val expectedMsg = "Timeout length must be positive, question not sent to [%s]. Sender[null] sent the message of type \"java.lang.String\"." format echo
       intercept[IllegalArgumentException] {
         Await.result(f, timeout.duration)
       }.getMessage should ===(expectedMsg)
diff --git a/akka-actor/src/main/scala/akka/pattern/AskSupport.scala b/akka-actor/src/main/scala/akka/pattern/AskSupport.scala
index 63484ece5c..5e819c7214 100644
--- a/akka-actor/src/main/scala/akka/pattern/AskSupport.scala
+++ b/akka-actor/src/main/scala/akka/pattern/AskSupport.scala
@@ -289,7 +289,7 @@ final class AskableActorRef(val actorRef: ActorRef) extends AnyVal {
       Future.failed[Any](new AskTimeoutException(s"""Recipient[$actorRef] had already been terminated. Sender[$sender] sent the message of type "${message.getClass.getName}"."""))
     case ref: InternalActorRef ⇒
       if (timeout.duration.length <= 0)
-        Future.failed[Any](new IllegalArgumentException(s"""Timeout length must not be negative, question not sent to [$actorRef]. Sender[$sender] sent the message of type "${message.getClass.getName}"."""))
+        Future.failed[Any](new IllegalArgumentException(s"""Timeout length must be positive, question not sent to [$actorRef]. Sender[$sender] sent the message of type "${message.getClass.getName}"."""))
       else {
         val a = PromiseActorRef(ref.provider, timeout, targetName = actorRef, message.getClass.getName, sender)
         actorRef.tell(message, a)
@@ -322,7 +322,7 @@ final class ExplicitlyAskableActorRef(val actorRef: ActorRef) extends AnyVal {
     case ref: InternalActorRef ⇒
       if (timeout.duration.length <= 0) {
         val message = messageFactory(ref.provider.deadLetters)
-        Future.failed[Any](new IllegalArgumentException(s"""Timeout length must not be negative, question not sent to [$actorRef]. Sender[$sender] sent the message of type "${message.getClass.getName}"."""))
+        Future.failed[Any](new IllegalArgumentException(s"""Timeout length must be positive, question not sent to [$actorRef]. Sender[$sender] sent the message of type "${message.getClass.getName}"."""))
       } else {
         val a = PromiseActorRef(ref.provider, timeout, targetName = actorRef, "unknown", sender)
         val message = messageFactory(a)
@@ -382,7 +382,7 @@ final class AskableActorSelection(val actorSel: ActorSelection) extends AnyVal {
     case ref: InternalActorRef ⇒
       if (timeout.duration.length <= 0)
         Future.failed[Any](
-          new IllegalArgumentException(s"""Timeout length must not be negative, question not sent to [$actorSel]. Sender[$sender] sent the message of type "${message.getClass.getName}"."""))
+          new IllegalArgumentException(s"""Timeout length must be positive, question not sent to [$actorSel]. Sender[$sender] sent the message of type "${message.getClass.getName}"."""))
       else {
         val a = PromiseActorRef(ref.provider, timeout, targetName = actorSel, message.getClass.getName, sender)
         actorSel.tell(message, a)
@@ -411,7 +411,7 @@ final class ExplicitlyAskableActorSelection(val actorSel: ActorSelection) extend
       if (timeout.duration.length <= 0) {
         val message = messageFactory(ref.provider.deadLetters)
         Future.failed[Any](
-          new IllegalArgumentException(s"""Timeout length must not be negative, question not sent to [$actorSel]. Sender[$sender] sent the message of type "${message.getClass.getName}"."""))
+          new IllegalArgumentException(s"""Timeout length must be positive, question not sent to [$actorSel]. Sender[$sender] sent the message of type "${message.getClass.getName}"."""))
       } else {
         val a = PromiseActorRef(ref.provider, timeout, targetName = actorSel, "unknown", sender)
         val message = messageFactory(a)
diff --git a/akka-typed/src/main/scala/akka/typed/Ask.scala b/akka-typed/src/main/scala/akka/typed/Ask.scala
index 458410de70..f63bc50966 100644
--- a/akka-typed/src/main/scala/akka/typed/Ask.scala
+++ b/akka-typed/src/main/scala/akka/typed/Ask.scala
@@ -42,7 +42,7 @@ object AskPattern {
       case ref: InternalActorRef ⇒
         if (timeout.duration.length <= 0)
           (ActorRef[U](ref.provider.deadLetters),
-            Future.failed[U](new IllegalArgumentException(s"Timeout length must not be negative, question not sent to [$actorRef]")))
+            Future.failed[U](new IllegalArgumentException(s"Timeout length must be positive, question not sent to [$actorRef]")))
         else {
           val a = PromiseActorRef(ref.provider, timeout, actorRef, "unknown")
           val b = ActorRef[U](a)