diff --git a/mercurial/obsutil.py b/mercurial/obsutil.py
--- a/mercurial/obsutil.py
+++ b/mercurial/obsutil.py
@@ -822,7 +822,7 @@ def markersusers(markers):
     """ Returns a sorted list of markers users without duplicates
     """
     markersmeta = [dict(m[3]) for m in markers]
-    users = set(meta.get('user') for meta in markersmeta if meta.get('user'))
+    users = set(meta['user'] for meta in markersmeta if meta.get('user'))
 
     return sorted(users)