diff -r c6e529c1f87c Tools/clinic/clinic.py
--- a/Tools/clinic/clinic.py	Fri Jan 24 22:28:42 2014 +0200
+++ b/Tools/clinic/clinic.py	Fri Jan 24 22:23:30 2014 -0600
@@ -3317,8 +3317,17 @@
                     bad = blacklist.bad
                 else:
                     # if they specify a c_default, we can be more lenient about the default value.
-                    # but at least ensure that we can turn it into text and reconstitute it correctly.
-                    bad = default != repr(eval(default))
+                    # but at least make an attempt at ensuring it's a valid expression.
+                    bad = False
+                    try:
+                        value = eval(default)
+                        if value == unspecified:
+                            fail("'unspecified' is not a legal default value!")
+                    except NameError:
+                        pass # probably a named constant
+                    except Exception as e:
+                        fail("Malformed expression given as default value\n"
+                             "{!r} caused {!r}".format(default, e))
                 if bad:
                     fail("Unsupported expression as default value: " + repr(default))