diff --git a/sarracenia/flow/__init__.py b/sarracenia/flow/__init__.py
index d75e9325b..9fb544ad5 100644
--- a/sarracenia/flow/__init__.py
+++ b/sarracenia/flow/__init__.py
@@ -2470,6 +2470,8 @@ def send(self, msg, options):
                     % local_file)
                 time.sleep(0.01)
                 return False
+            elif 'size' not in msg:
+                msg['size'] = os.path.getsize(local_file)
 
             offset = 0
             if ('blocks' in msg) and (msg['blocks']['method'] == 'inplace'):