diff --git a/mercurial/phases.py b/mercurial/phases.py
--- a/mercurial/phases.py
+++ b/mercurial/phases.py
@@ -599,8 +599,8 @@ def updatephases(repo, trgetter, headsby
     # to update. This avoid creating empty transaction during no-op operation.
 
     for phase in allphases[:-1]:
-        revset = '%%ln - _phase(%d)' % phase
-        heads = [c.node() for c in repo.set(revset, headsbyphase[phase])]
+        revset = '%ln - _phase(%s)'
+        heads = [c.node() for c in repo.set(revset, headsbyphase[phase], phase)]
         if heads:
             advanceboundary(repo, trgetter(), phase, heads)