Index: Lib/lib-tk/FixTk.py
===================================================================
--- Lib/lib-tk/FixTk.py	(revision 76258)
+++ Lib/lib-tk/FixTk.py	(working copy)
@@ -20,9 +20,12 @@
 else:
     def convert_path(s):
         if isinstance(s, str):
-            s = s.decode("mbcs")
+            u = s.decode("mbcs")
+        else:
+            u = s
+        assert isinstance(u, unicode)
         hdir = ctypes.windll.kernel32.\
-            CreateFileW(s, 0x80,    # FILE_READ_ATTRIBUTES
+            CreateFileW(u, 0x80,    # FILE_READ_ATTRIBUTES
                         1,          # FILE_SHARE_READ
                         None, 3,    # OPEN_EXISTING
                         0x02000000, # FILE_FLAG_BACKUP_SEMANTICS
@@ -38,10 +41,11 @@
         if res == 0:
             # Conversion failed (e.g. network location)
             return s
-        s = buf[:res]
+        u = buf[:res]
         # Ignore leading \\?\
-        if s.startswith(u"\\\\?\\"):
-            s = s[4:]
+        if u.startswith(u"\\\\?\\"):
+            u = u[4:]
+        s = u.encode("mbcs")
         return s
 
 prefix = os.path.join(sys.prefix,"tcl")