diff --git a/bin/lib/item_basic.py b/bin/lib/item_basic.py
index 71fa5378..b35d126e 100755
--- a/bin/lib/item_basic.py
+++ b/bin/lib/item_basic.py
@@ -209,7 +209,10 @@ def _get_dir_source_name(directory, source_name=None, l_sources_name=set(), filt
         l_dir = os.listdir(directory)
     # empty directory
     if not l_dir:
-        return l_sources_name.add(source_name)
+        if source_name:
+            return l_sources_name.add(source_name)
+        else:
+            return l_sources_name
     else:
         for src_name in l_dir:
             if len(src_name) == 4: