diff --git a/mercurial/filelog.py b/mercurial/filelog.py
--- a/mercurial/filelog.py
+++ b/mercurial/filelog.py
@@ -12,8 +12,8 @@ demandload(globals(), "os")
 class filelog(revlog):
     def __init__(self, opener, path, defversion=REVLOG_DEFAULT_VERSION):
         revlog.__init__(self, opener,
-                        os.path.join("data", self.encodedir(path + ".i")),
-                        os.path.join("data", self.encodedir(path + ".d")),
+                        "/".join(("data", self.encodedir(path + ".i"))),
+                        "/".join(("data", self.encodedir(path + ".d"))),
                         defversion)
 
     # This avoids a collision between a file named foo and a dir named