diff --git a/src/servicex_did_finder_lib/did_finder_app.py b/src/servicex_did_finder_lib/did_finder_app.py
index 87407e5..b167f4e 100644
--- a/src/servicex_did_finder_lib/did_finder_app.py
+++ b/src/servicex_did_finder_lib/did_finder_app.py
@@ -97,8 +97,11 @@ def do_lookup(self, did: str, dataset_id: int, endpoint: str, user_did_finder: U
         try:
             for file_info in user_did_finder(did_info.did, info, self.app.did_finder_args):
                 acc.add(file_info)
+                if did_info.file_count == -1:
+                    acc.send_on(-1)  # if looking up full dataset, can send partial results
 
-            acc.send_on(did_info.file_count)
+            if did_info.file_count > 0:  # otherwise wait until all files arrive, then limit results
+                acc.send_on(did_info.file_count)
         except Exception:
             # noinspection PyTypeChecker
             self.logger.error(