diff -r b7f248eae2bc Lib/tkinter/tix.py
--- a/Lib/tkinter/tix.py	Mon Jan 02 02:50:33 2017 -0500
+++ b/Lib/tkinter/tix.py	Mon Jan 02 18:12:27 2017 +0200
@@ -204,8 +204,9 @@ class Tk(tkinter.Tk, tixCommand):
         tixlib = os.environ.get('TIX_LIBRARY')
         self.tk.eval('global auto_path; lappend auto_path [file dir [info nameof]]')
         if tixlib is not None:
-            self.tk.eval('global auto_path; lappend auto_path {%s}' % tixlib)
-            self.tk.eval('global tcl_pkgPath; lappend tcl_pkgPath {%s}' % tixlib)
+            self.tk.setvar('TIX_LIBRARY', tixlib)
+            self.tk.eval('global auto_path; lappend auto_path $TIX_LIBRARY')
+            self.tk.eval('global tcl_pkgPath; lappend tcl_pkgPath $TIX_LIBRARY')
         # Load Tix - this should work dynamically or statically
         # If it's static, tcl/tix8.1/pkgIndex.tcl should have
         #               'load {} Tix'