--- a/hgext/fsmonitor/watchmanclient.py	Mon Nov 04 10:09:08 2019 +0100
+++ b/hgext/fsmonitor/watchmanclient.py	Sat Nov 02 12:42:23 2019 -0700
@@ -10,6 +10,7 @@
 import getpass
 
 from mercurial import util
+from mercurial.utils import procutil
 
 from . import pywatchman
 
@@ -92,7 +93,7 @@
                 self._watchmanclient = pywatchman.client(
                     timeout=self._timeout,
                     useImmutableBser=True,
-                    watchman_exe=watchman_exe,
+                    binpath=procutil.tonativestr(watchman_exe),
                 )
             return self._watchmanclient.query(*watchmanargs)
         except pywatchman.CommandError as ex: