diff --git a/hgext/fsmonitor/__init__.py b/hgext/fsmonitor/__init__.py
--- a/hgext/fsmonitor/__init__.py
+++ b/hgext/fsmonitor/__init__.py
@@ -336,7 +336,7 @@ def overridewalk(orig, self, match, subr
     nonnormalset = {
         f
         for f, e in self._map.items()
-        if e.v1_state() != "n" or e.v1_mtime() == -1
+        if e.v1_state() != b"n" or e.v1_mtime() == -1
     }
 
     copymap = self._map.copymap