diff --git a/grpc.go b/grpc.go
index 9c4b3a7..71d7af1 100644
--- a/grpc.go
+++ b/grpc.go
@@ -263,7 +263,7 @@ func (g *Server) handler(srv interface{}, stream grpc.ServerStream) error {
 	// create new context
 	ctx = metadata.NewIncomingContext(ctx, md)
 	ctx = metadata.NewOutgoingContext(ctx, metadata.New(0))
-	ctx = context.WithValue(ctx, rspMetadataKey{}, &rspMetadataVal{})
+	ctx = context.WithValue(ctx, rspMetadataKey{}, &rspMetadataVal{m: metadata.New(0)})
 
 	stream = &streamWrapper{ctx, stream}