diff --git a/ostap/parallel/parallel_statvar.py b/ostap/parallel/parallel_statvar.py
index 393b8418..d0758acd 100644
--- a/ostap/parallel/parallel_statvar.py
+++ b/ostap/parallel/parallel_statvar.py
@@ -18,6 +18,7 @@
 # =============================================================================
 from   ostap.parallel.parallel import Task, WorkManager
 from   ostap.core.core         import VE
+from   ostap.core.meta_info    import root_info, python_info 
 import ROOT
 # =============================================================================
 # logging 
@@ -126,16 +127,20 @@ def pStatVar ( chain               ,
     """
     ## few special/trivial cases
 
-    last = min ( n_large , first + nevents if 0 < nevents else n_large )
     
+    from ostap.trees.trees  import _stat_vars_
+    last = min ( n_large , first + nevents if 0 < nevents else n_large )
+        
     if 0 <= first and 0 < nevents < chunk_size :
         return chain.statVar ( what , cuts , first , last )
     elif isinstance ( chain , ROOT.TChain ) :
         if 1 == chain.nFiles() and len ( chain ) < chunk_size :
             return chain.statVar ( what , cuts , first , last )                         
     elif isinstance ( chain , ROOT.TTree  ) and len ( chain ) < chunk_size :
-        return chain.statVar ( what , cuts , first , last ) 
-    
+        return chain.statVar ( what , cuts , first , last )
+    elif ( 6 , 18 ) <= root_info < ( 6 , 19 ) and python_info < ( 3 , 0 ) :
+        return chain.statVar ( what , cuts , first , last )
+        
     from ostap.trees.trees import Chain
     ch     = Chain ( chain , first = first , nevents = nevents )