diff --git a/ostap/io/tests/test_io_dbases.py b/ostap/io/tests/test_io_dbases.py
index ffc7a0e7..8ceb95d3 100644
--- a/ostap/io/tests/test_io_dbases.py
+++ b/ostap/io/tests/test_io_dbases.py
@@ -36,6 +36,7 @@ def the_name ():
     # =============================================================================
     index = 1
     def the_name () :
+        global index 
         index += 1
         return 'i%08d' % index 
     # =============================================================================