diff --git a/heudiconv/heuristics/reproin.py b/heudiconv/heuristics/reproin.py
index bbf657f0..a295740a 100644
--- a/heudiconv/heuristics/reproin.py
+++ b/heudiconv/heuristics/reproin.py
@@ -124,6 +124,9 @@
 
 - We replace all ( with { and ) with } to be able e.g. to specify session {date}
 - "WIP " prefix unconditionally added by the scanner is stripped
+
+
+-Michael-Sun Plans on adding a heuristic to deal with ses-X* instances
 """
 
 import os
@@ -780,6 +783,13 @@ def infotoids(seqinfos, outdir):
                     "Should have got a single session marker.  Got following: %s"
                     % ', '.join(map(repr, ses_markers))
                 )
+            if re.match("(X|x)*", ses_markers):
+               # replace X* or x* sessions with prior_sessions+1
+               prior_sessions = sorted(glob(os.path.join(sessions_dir, 'ses-*')))
+               if prior_sessions:
+                session = '%03d' % (len(prior_sessions) + 1)
+               else:
+                session='001'
             session = ses_markers[0]
         else:
             # TODO - I think we are doomed to go through the sequence and split