diff --git a/mercurial/dirstate.py b/mercurial/dirstate.py
--- a/mercurial/dirstate.py
+++ b/mercurial/dirstate.py
@@ -65,6 +65,10 @@ class dirstate(object):
         return self._copymap
 
     @propertycache
+    def _normroot(self):
+        return util.normcase(self._root)
+
+    @propertycache
     def _foldmap(self):
         f = {}
         for name in self._map:
@@ -384,7 +388,7 @@ class dirstate(object):
                 folded = path
             else:
                 folded = self._foldmap.setdefault(normed,
-                                util.fspath(path, self._root))
+                                util.fspath(normed, self._normroot))
         return folded
 
     def normalize(self, path, isknown=False):
diff --git a/mercurial/util.py b/mercurial/util.py
--- a/mercurial/util.py
+++ b/mercurial/util.py
@@ -616,10 +616,10 @@ def fspath(name, root):
     The name is either relative to root, or it is an absolute path starting
     with root. Note that this function is unnecessary, and should not be
     called, for case-sensitive filesystems (simply because it's expensive).
+
+    Both name and root should be normcase-ed.
     '''
     # If name is absolute, make it relative
-    name = normcase(name)
-    root = normcase(root)
     if name.startswith(root):
         l = len(root)
         if name[l] == os.sep or name[l] == os.altsep: