diff -r e7be7aceab77 Lib/tkinter/test/widget_tests.py
--- a/Lib/tkinter/test/widget_tests.py	Sun Nov 03 18:25:17 2013 +0200
+++ b/Lib/tkinter/test/widget_tests.py	Sun Nov 03 18:31:56 2013 +0200
@@ -8,10 +8,21 @@
 
 noconv = str if tcl_version < (8, 5) else False
 
+pixels_round = round
+if tcl_version[:2] == (8, 5):
+    # Workaround a bug in Tk
+    # http://core.tcl.tk/tk/info/3497848
+    root = setup_master()
+    patchlevel = root.call('info', 'patchlevel')
+    patchlevel = tuple(map(int, patchlevel.split('.')))
+    if patchlevel < (8, 5, 12):
+        pixels_round = int
+
+
 _sentinel = object()
 
 class AbstractWidgetTest:
-    _conv_pixels = round
+    _conv_pixels = pixels_round
     _conv_pad_pixels = None
     wantobjects = True