diff --git a/proto/caosdb/entity/v1alpha1/main.proto b/proto/caosdb/entity/v1alpha1/main.proto
index c06a0a68a26835926072f86a8c182f01f485f93e..fe46850ac1bb2318db504bfd569021bd11437c40 100644
--- a/proto/caosdb/entity/v1alpha1/main.proto
+++ b/proto/caosdb/entity/v1alpha1/main.proto
@@ -740,5 +740,5 @@ service FileTransmissionService {
   rpc FileUpload(stream FileUploadRequest) returns (FileUploadResponse);
   // A file download. The download has to be registered prior this rpc in the
   // RetrieveRequest.
-  rpc FileDownload(FileDownloadRequest) returns (FileDownloadResponse);
+  rpc FileDownload(FileDownloadRequest) returns (stream FileDownloadResponse);
 }