diff -r 00d09afb57ca Lib/test/test___all__.py
--- a/Lib/test/test___all__.py	Fri Dec 20 22:14:03 2013 +1000
+++ b/Lib/test/test___all__.py	Fri Dec 20 11:39:13 2013 -0600
@@ -112,6 +112,10 @@
                   ignored)
             print('Following modules failed to be imported:', failed_imports)
 
+def tearDownModule():
+    # Remove tkinter's changes to os.environ to avoid warnings from regrtest
+    from tkinter._fix import unfix_environ
+    unfix_environ()
 
 if __name__ == "__main__":
     unittest.main()
diff -r 00d09afb57ca Lib/test/test_idle.py
--- a/Lib/test/test_idle.py	Fri Dec 20 22:14:03 2013 +1000
+++ b/Lib/test/test_idle.py	Fri Dec 20 11:39:13 2013 -0600
@@ -23,6 +23,11 @@
 # load_tests() if it finds it. (Unittest.main does the same.)
 load_tests = idletest.load_tests
 
+def tearDownModule():
+    # Remove changes to os.environ to avoid warnings from regrtest
+    from tkinter._fix import unfix_environ
+    unfix_environ()
+
 if __name__ == '__main__':
     # Until unittest supports resources, we emulate regrtest's -ugui
     # so loaded tests run the same as if textually present here.
diff -r 00d09afb57ca Lib/test/test_tcl.py
--- a/Lib/test/test_tcl.py	Fri Dec 20 22:14:03 2013 +1000
+++ b/Lib/test/test_tcl.py	Fri Dec 20 11:39:13 2013 -0600
@@ -9,9 +9,6 @@
 # Skip this test if the _tkinter module wasn't built.
 _tkinter = support.import_module('_tkinter')
 
-# Make sure tkinter._fix runs to set up the environment
-support.import_fresh_module('tkinter')
-
 from tkinter import Tcl
 from _tkinter import TclError
 
@@ -273,9 +270,11 @@
         tcl = Tcl()
         print('patchlevel =', tcl.call('info', 'patchlevel'))
 
+def tearDownModule():
+    # Remove changes to os.environ to avoid warnings from regrtest
+    from tkinter._fix import unfix_environ
+    unfix_environ()
 
-def test_main():
-    support.run_unittest(TclTest, TkinterTest, BigmemTclTest)
 
 if __name__ == "__main__":
-    test_main()
+    unittest.main()
diff -r 00d09afb57ca Lib/test/test_tk.py
--- a/Lib/test/test_tk.py	Fri Dec 20 22:14:03 2013 +1000
+++ b/Lib/test/test_tk.py	Fri Dec 20 11:39:13 2013 -0600
@@ -2,9 +2,6 @@
 # Skip test if _tkinter wasn't built.
 support.import_module('_tkinter')
 
-# Make sure tkinter._fix runs to set up the environment
-support.import_fresh_module('tkinter')
-
 # Skip test if tk cannot be initialized.
 from tkinter.test.support import check_tk_availability
 check_tk_availability()
@@ -21,5 +18,9 @@
     support.run_unittest(
             *runtktests.get_tests(text=False, packages=['test_tkinter']))
 
+    # Remove changes to os.environ to avoid warnings from regrtest
+    from tkinter._fix import unfix_environ
+    unfix_environ()
+
 if __name__ == '__main__':
     test_main(enable_gui=True)
diff -r 00d09afb57ca Lib/test/test_ttk_guionly.py
--- a/Lib/test/test_ttk_guionly.py	Fri Dec 20 22:14:03 2013 +1000
+++ b/Lib/test/test_ttk_guionly.py	Fri Dec 20 11:39:13 2013 -0600
@@ -5,9 +5,6 @@
 # Skip this test if _tkinter wasn't built.
 support.import_module('_tkinter')
 
-# Make sure tkinter._fix runs to set up the environment
-support.import_fresh_module('tkinter')
-
 # Skip test if tk cannot be initialized.
 from tkinter.test.support import check_tk_availability
 check_tk_availability()
@@ -34,7 +31,12 @@
         support.run_unittest(
                 *runtktests.get_tests(text=False, packages=['test_ttk']))
     finally:
+        # don't leave a window hanging around
         get_tk_root().destroy()
 
+    # Remove changes to os.environ to avoid warnings from regrtest
+    from tkinter._fix import unfix_environ
+    unfix_environ()
+
 if __name__ == '__main__':
     test_main(enable_gui=True)
diff -r 00d09afb57ca Lib/test/test_ttk_textonly.py
--- a/Lib/test/test_ttk_textonly.py	Fri Dec 20 22:14:03 2013 +1000
+++ b/Lib/test/test_ttk_textonly.py	Fri Dec 20 11:39:13 2013 -0600
@@ -4,14 +4,15 @@
 # Skip this test if _tkinter does not exist.
 support.import_module('_tkinter')
 
-# Make sure tkinter._fix runs to set up the environment
-support.import_fresh_module('tkinter')
-
 from tkinter.test import runtktests
 
 def test_main():
     support.run_unittest(
             *runtktests.get_tests(gui=False, packages=['test_ttk']))
 
+    # Remove changes to os.environ to avoid warnings from regrtest
+    from tkinter._fix import unfix_environ
+    unfix_environ()
+
 if __name__ == '__main__':
     test_main()
diff -r 00d09afb57ca Lib/tkinter/_fix.py
--- a/Lib/tkinter/_fix.py	Fri Dec 20 22:14:03 2013 +1000
+++ b/Lib/tkinter/_fix.py	Fri Dec 20 11:39:13 2013 -0600
@@ -46,6 +46,9 @@
             s = "\\" + s[3:]
         return s
 
+orig_environ = os.environ.copy()
+
+# Add (TCL|TK|TIX)_LIBRARY vars to os.environ so init.tcl can be found
 prefix = os.path.join(sys.base_prefix,"tcl")
 if not os.path.exists(prefix):
     # devdir/../tcltk/lib
@@ -76,3 +79,14 @@
                 tixdir = os.path.join(prefix,name)
                 if os.path.isdir(tixdir):
                     os.environ["TIX_LIBRARY"] = tixdir
+
+def unfix_environ(orig_environ=orig_environ):
+    # Use this function to undo the changes made by fix_environ()
+    for var in ['TCL_LIBRARY', 'TK_LIBRARY', 'TIX_LIBRARY']:
+        if var not in orig_environ:
+            os.environ.pop(var, None)
+
+    # Make sure the environment is fixed again next time tkinter is imported
+    del sys.modules['tkinter._fix']
+
+del orig_environ