diff --git a/src/nlsat/nlsat_params.pyg b/src/nlsat/nlsat_params.pyg
index b0e0c884f..048fcf521 100644
--- a/src/nlsat/nlsat_params.pyg
+++ b/src/nlsat/nlsat_params.pyg
@@ -25,6 +25,6 @@ def_module_params('nlsat',
                           ('lws', BOOL, True, "apply levelwise."),
                           ('lws_spt_threshold', UINT, 4, "minimum both-side polynomial count to apply spanning tree optimization; < 2 disables spanning tree"),
                           ('lws_witness_subs_lc', BOOL, True, "try substitute the non-nullified witness by the lc"),
-                          ('lws_witness_subs_disc', BOOL, False, "try substitute the non-nullified witness by the discriminant"),
+                          ('lws_witness_subs_disc', BOOL, True, "try substitute the non-nullified witness by the discriminant"),
                           ('canonicalize', BOOL, True, "canonicalize polynomials.")
                           ))