diff --git a/atdb/taskdatabase/services/specification/input_validation.py b/atdb/taskdatabase/services/specification/input_validation.py
index 8000ad8b90fd96a8581338bf8a268f0b5a9da4e5..070c5392589d74e6bdc64278a857cbb123c21730 100644
--- a/atdb/taskdatabase/services/specification/input_validation.py
+++ b/atdb/taskdatabase/services/specification/input_validation.py
@@ -61,7 +61,7 @@ def check_duplicates(data):
 
     if not data:
         # tasks without inputs should just return
-        return False,None
+        return False,None,None
 
     found_duplicates = False
     seen_surls = set()
@@ -80,7 +80,7 @@ def check_duplicates(data):
             found_duplicates = True
             logger.info(f'duplicate found: {filename_without_hash}')
 
-    return found_duplicates,duplicates, unique_inputs
+    return found_duplicates,duplicates,unique_inputs
 
 
 def recalculate_size(data):