diff --git a/src/math/lp/nla_intervals.cpp b/src/math/lp/nla_intervals.cpp
index 38daa93ac..a51e878e7 100644
--- a/src/math/lp/nla_intervals.cpp
+++ b/src/math/lp/nla_intervals.cpp
@@ -90,6 +90,7 @@ bool intervals::check_interval_for_conflict_on_zero_upper(const interval & i) {
      svector<lp::constraint_index> expl;
      m_dep_manager.linearize(i.m_upper_dep, expl); 
      _().current_expl().add_expl(expl);
+     TRACE("nla_cn", print_lemma(tout););
      return true;
 }