diff --git a/akka-actor/src/main/scala/akka/actor/ActorRef.scala b/akka-actor/src/main/scala/akka/actor/ActorRef.scala
index dbaf013705..a9b74e071f 100644
--- a/akka-actor/src/main/scala/akka/actor/ActorRef.scala
+++ b/akka-actor/src/main/scala/akka/actor/ActorRef.scala
@@ -1237,7 +1237,7 @@ private[akka] case class RemoteActorRef private[akka] (
 
   def postMessageToMailbox(message: Any, senderOption: Option[ActorRef]): Unit =
     RemoteClientModule.send[Any](
-      message, senderOption, None, remoteAddress.get, timeout, true, this, None, actorType)
+      message, senderOption, None, remoteAddress.get, timeout, true, this, None, actorType, loader)
 
   def postMessageToMailboxAndCreateFutureResultWithTimeout[T](
     message: Any,
@@ -1245,7 +1245,7 @@ private[akka] case class RemoteActorRef private[akka] (
     senderOption: Option[ActorRef],
     senderFuture: Option[CompletableFuture[T]]): CompletableFuture[T] = {
     val future = RemoteClientModule.send[T](
-      message, senderOption, senderFuture, remoteAddress.get, timeout, false, this, None, actorType)
+      message, senderOption, senderFuture, remoteAddress.get, timeout, false, this, None, actorType, loader)
     if (future.isDefined) future.get
     else throw new IllegalActorStateException("Expected a future from remote call to actor " + toString)
   }
diff --git a/akka-actor/src/main/scala/akka/util/ReflectiveAccess.scala b/akka-actor/src/main/scala/akka/util/ReflectiveAccess.scala
index 94661b9f1e..a22aa918cd 100644
--- a/akka-actor/src/main/scala/akka/util/ReflectiveAccess.scala
+++ b/akka-actor/src/main/scala/akka/util/ReflectiveAccess.scala
@@ -92,9 +92,10 @@ object ReflectiveAccess extends Logging {
       isOneWay: Boolean,
       actorRef: ActorRef,
       typedActorInfo: Option[Tuple2[String, String]],
-      actorType: ActorType): Option[CompletableFuture[T]] = {
+      actorType: ActorType,
+      loader: Option[ClassLoader] = None): Option[CompletableFuture[T]] = {
       ensureEnabled
-      clientFor(remoteAddress.getHostName, remoteAddress.getPort, None).send[T](
+      clientFor(remoteAddress.getHostName, remoteAddress.getPort, loader).send[T](
         message, senderOption, senderFuture, remoteAddress, timeout, isOneWay, actorRef, typedActorInfo, actorType)
     }
   }
diff --git a/akka-remote/src/main/scala/akka/remote/MessageSerializer.scala b/akka-remote/src/main/scala/akka/remote/MessageSerializer.scala
index b68bb0bca6..aca0333582 100644
--- a/akka-remote/src/main/scala/akka/remote/MessageSerializer.scala
+++ b/akka-remote/src/main/scala/akka/remote/MessageSerializer.scala
@@ -11,17 +11,18 @@ import akka.util._
 import com.google.protobuf.{Message, ByteString}
 
 object MessageSerializer extends Logging {
-  private var SERIALIZER_JAVA:       Serializer.Java      = Serializer.Java
-  private var SERIALIZER_JAVA_JSON:  Serializer.JavaJSON  = Serializer.JavaJSON
-  private var SERIALIZER_SCALA_JSON: Serializer.ScalaJSON = Serializer.ScalaJSON
-  private var SERIALIZER_SBINARY:    Serializer.SBinary   = Serializer.SBinary
-  private var SERIALIZER_PROTOBUF:   Serializer.Protobuf  = Serializer.Protobuf
+  private def SERIALIZER_JAVA:       Serializer.Java      = Serializer.Java
+  private def SERIALIZER_JAVA_JSON:  Serializer.JavaJSON  = Serializer.JavaJSON
+  private def SERIALIZER_SCALA_JSON: Serializer.ScalaJSON = Serializer.ScalaJSON
+  private def SERIALIZER_SBINARY:    Serializer.SBinary   = Serializer.SBinary
+  private def SERIALIZER_PROTOBUF:   Serializer.Protobuf  = Serializer.Protobuf
 
   def setClassLoader(cl: ClassLoader) = {
-    SERIALIZER_JAVA.classLoader       = Some(cl)
-    SERIALIZER_JAVA_JSON.classLoader  = Some(cl)
-    SERIALIZER_SCALA_JSON.classLoader = Some(cl)
-    SERIALIZER_SBINARY.classLoader    = Some(cl)
+    val someCl = Some(cl)
+    SERIALIZER_JAVA.classLoader       = someCl
+    SERIALIZER_JAVA_JSON.classLoader  = someCl
+    SERIALIZER_SCALA_JSON.classLoader = someCl
+    SERIALIZER_SBINARY.classLoader    = someCl
   }
 
   def deserialize(messageProtocol: MessageProtocol): Any = {
diff --git a/akka-remote/src/main/scala/akka/serialization/Serializer.scala b/akka-remote/src/main/scala/akka/serialization/Serializer.scala
index e30e615322..20c91c8559 100644
--- a/akka-remote/src/main/scala/akka/serialization/Serializer.scala
+++ b/akka-remote/src/main/scala/akka/serialization/Serializer.scala
@@ -18,7 +18,7 @@ import sjson.json.{Serializer => SJSONSerializer}
  * @author <a href="http://jonasboner.com">Jonas Bon&#233;r</a>
  */
 @serializable trait Serializer {
-  var classLoader: Option[ClassLoader] = None
+  @volatile var classLoader: Option[ClassLoader] = None
   def deepClone(obj: AnyRef): AnyRef = fromBinary(toBinary(obj), Some(obj.getClass))
 
   def toBinary(obj: AnyRef): Array[Byte]