diff --git a/src/sat/sat_aig_simplifier.cpp b/src/sat/sat_aig_simplifier.cpp
index 5b714f22a..57d71e803 100644
--- a/src/sat/sat_aig_simplifier.cpp
+++ b/src/sat/sat_aig_simplifier.cpp
@@ -508,7 +508,7 @@ namespace sat {
     }
 
     /**
-     * Equilvalences modulo cuts are not necessarily DRAT derivable.
+     * Equivalences modulo cuts are not necessarily DRAT derivable.
      * To ensure that there is a DRAT derivation we create all resolvents
      * of the LUT clauses until deriving binary u or ~v and ~u or v.
      * each resolvent is DRAT derivable because there are two previous lemmas that
diff --git a/src/smt/params/smt_params_helper.pyg b/src/smt/params/smt_params_helper.pyg
index 119e537c5..22b252985 100644
--- a/src/smt/params/smt_params_helper.pyg
+++ b/src/smt/params/smt_params_helper.pyg
@@ -76,7 +76,7 @@ def_module_params(module_name='smt',
                           ('arith.simplex_strategy', UINT, 0, 'simplex strategy for the solver'),
                           ('arith.enable_hnf', BOOL, True, 'enable hnf (Hermite Normal Form) cuts'),
                           ('arith.bprop_on_pivoted_rows', BOOL, True, 'propagate bounds on rows changed by the pivot operation'),
-                          ('arith.nla', BOOL, False, 'call nonlinear integer solver with incremental linearization'),
+                          ('arith.nla', BOOL, True, 'call nonlinear solver'),
                           ('arith.print_ext_var_names', BOOL, False, 'print external variable names'),
                           ('pb.conflict_frequency', UINT, 1000, 'conflict frequency for Pseudo-Boolean theory'),
                           ('pb.learn_complements', BOOL, True, 'learn complement literals for Pseudo-Boolean theory'),
diff --git a/src/smt/theory_lra.cpp b/src/smt/theory_lra.cpp
index 45fff2d4e..8f81d2096 100644
--- a/src/smt/theory_lra.cpp
+++ b/src/smt/theory_lra.cpp
@@ -266,7 +266,6 @@ class theory_lra::imp {
 
     // non-linear arithmetic
     scoped_ptr<nra::solver>  m_nra;
-    bool                     m_use_nla;
     scoped_ptr<nla::solver>  m_nla;
     bool                     m_use_nra_model;
     scoped_ptr<scoped_anum>  m_a1, m_a2;
@@ -292,25 +291,17 @@ class theory_lra::imp {
         }
         
         void push() {
-            if (m_use_nla) {
-                if (m_nla != nullptr)
-                    (*m_nla)->push();
-            }
-            else {
-                if (m_nra != nullptr)
-                    (*m_nra)->push();
-            }
+            if (m_nla != nullptr)
+                (*m_nla)->push();
+            if (m_nra != nullptr)
+                (*m_nra)->push();
         }
 
         void pop(unsigned scopes) {
-            if (m_use_nla) {
-                if (m_nla != nullptr)
-                    (*m_nla)->pop(scopes);
-            }
-            else {
-                if (m_nra != nullptr)
-                    (*m_nra)->pop(scopes);
-            }
+            if (m_nla != nullptr)
+                (*m_nla)->pop(scopes);
+            if (m_nra != nullptr)
+                (*m_nra)->pop(scopes);
         }
 
         
@@ -404,7 +395,7 @@ class theory_lra::imp {
 
         lp().settings().m_int_run_gcd_test = ctx().get_fparams().m_arith_gcd_test;
         lp().settings().set_random_seed(ctx().get_fparams().m_random_seed);
-        m_switcher.m_use_nla = m_use_nla = lpar.arith_nla();
+        m_switcher.m_use_nla = lpar.arith_nla();
         m_lia = alloc(lp::int_solver, *m_solver.get());
         get_one(true);
         get_zero(true);
@@ -1613,12 +1604,7 @@ public:
     }
 
     bool influences_nl_var(theory_var v) const {
-        if (!m_use_nla)            
-            return false; // that is the legacy solver behavior
-        if (!m_nla)
-            return false;
-            
-        return m_nla->influences_nl_var(get_lpvar(v));
+        return m_nla && m_nla->influences_nl_var(get_lpvar(v));
     }
     
     bool can_be_used_in_random_update(theory_var v) const {
@@ -1716,7 +1702,7 @@ public:
 
     bool is_eq(theory_var v1, theory_var v2) {
         if (m_use_nra_model) {
-            lp_assert(!m_use_nla);
+            SASSERT(!m_switcher.m_use_nla);
             return m_nra->am().eq(nl_value(v1, *m_a1), nl_value(v2, *m_a2));
         }
         else {
@@ -3342,6 +3328,13 @@ public:
                 ctx().mark_as_relevant(c);
             }
             TRACE("arith", ctx().display_literals_verbose(tout, m_core) << "\n";);
+            DEBUG_CODE(
+                for (literal const& c : m_core) {
+                    if (ctx().get_assignment(c) == l_true) {
+                        TRACE("arith", ctx().display_literal_verbose(tout, c) << " is true\n";);
+                        SASSERT(false);
+                    }
+                });
             ctx().mk_th_axiom(get_id(), m_core.size(), m_core.c_ptr());
         }
     }