diff -r 9aba650eea6b -r 20807d3d7cf6 server/querier.py
--- a/server/querier.py	Wed Mar 30 11:07:16 2011 +0200
+++ b/server/querier.py	Wed Mar 30 11:08:15 2011 +0200
@@ -354,7 +354,7 @@
                     myrqlst = select.copy(solutions=lchecksolutions)
                     myunion.append(myrqlst)
                     # in-place rewrite + annotation / simplification
-                    lcheckdef = [((var, 'X'), rqlexprs) for var, rqlexprs in lcheckdef]
+                    lcheckdef = [({var: 'X'}, rqlexprs) for var, rqlexprs in lcheckdef]
                     rewrite(myrqlst, lcheckdef, lchecksolutions, self.args)
                     add_noinvariant(noinvariant, restricted, myrqlst, nbtrees)
                 if () in localchecks: