diff --git a/scalapb-runtime-grpc/src/main/scala/scalapb/grpc/Marshaller.scala b/scalapb-runtime-grpc/src/main/scala/scalapb/grpc/Marshaller.scala
index ee41110ca..a2d8eada4 100644
--- a/scalapb-runtime-grpc/src/main/scala/scalapb/grpc/Marshaller.scala
+++ b/scalapb-runtime-grpc/src/main/scala/scalapb/grpc/Marshaller.scala
@@ -6,10 +6,10 @@ import scalapb.{GeneratedMessage, GeneratedMessageCompanion, TypeMapper}
 
 class Marshaller[T <: GeneratedMessage](companion: GeneratedMessageCompanion[T])
     extends io.grpc.MethodDescriptor.Marshaller[T] {
-  override def stream(t: T): InputStream = new ProtoInputStream[T](t, this)
+  override def stream(t: T): InputStream = new ProtoInputStream[T](t)
 
   override def parse(inputStream: InputStream): T = inputStream match {
-    case pis: ProtoInputStream[T] if pis.marshaller == this => pis.message
+    case pis: ProtoInputStream[_] => pis.message.asInstanceOf[T]
     case _ => companion.parseFrom(inputStream)
   }
 }
diff --git a/scalapb-runtime-grpc/src/main/scala/scalapb/grpc/ProtoInputStream.scala b/scalapb-runtime-grpc/src/main/scala/scalapb/grpc/ProtoInputStream.scala
index a892dc433..1583845ef 100644
--- a/scalapb-runtime-grpc/src/main/scala/scalapb/grpc/ProtoInputStream.scala
+++ b/scalapb-runtime-grpc/src/main/scala/scalapb/grpc/ProtoInputStream.scala
@@ -9,7 +9,7 @@ import java.io.{ByteArrayInputStream, InputStream}
   * Allows skipping serialization completely when the io.grpc.inprocess.InProcessTransport is used.
   * Inspired by https://github.com/grpc/grpc-java/blob/master/protobuf-lite/src/main/java/io/grpc/protobuf/lite/ProtoInputStream.java
   */
-class ProtoInputStream[T <: GeneratedMessage](msg: T, val marshaller: Marshaller[T]) extends InputStream {
+class ProtoInputStream[T <: GeneratedMessage](msg: T) extends InputStream {
 
   private var state: State = Message(msg)