diff --git a/XAS.py b/XAS.py
index 8f4ae67744ac79647f3ad74100f2b67d66cece94..c7605d587356b90b20880468f076d4c5083163e8 100644
--- a/XAS.py
+++ b/XAS.py
@@ -122,7 +122,7 @@ def xas(nrun, bins=None, Iokey='SCS_SA3', Itkey='MCP3apd', nrjkey='nrj', Iooffse
                 counts: the number of events in each bin
     """
     
-    stacked = nrun.stack(x=['trainId','sa3_pId'])
+    stacked = nrun.stack(dummy_=['trainId','sa3_pId'])
 
     Io = stacked[Iokey].values + Iooffset
     It = stacked[Itkey].values