diff --git a/src/sat/smt/dt_solver.cpp b/src/sat/smt/dt_solver.cpp
index 22e446a13..daecb7325 100644
--- a/src/sat/smt/dt_solver.cpp
+++ b/src/sat/smt/dt_solver.cpp
@@ -554,12 +554,12 @@ namespace dt {
     }
 
     // Assuming `app` is equal to a constructor term, return the constructor enode
-    inline euf::enode* solver::oc_get_cstor(enode* app) {
+    inline euf::enode* solver::oc_get_cstor(enode* app) const {
         theory_var v = app->get_root()->get_th_var(get_id());
-        SASSERT(v != euf::null_theory_var);
+        if (v == euf::null_theory_var)
+            return nullptr;
         v = m_find.find(v);
         var_data* d = m_var_data[v];
-        SASSERT(d->m_constructor);
         return d->m_constructor;
     }
 
@@ -783,7 +783,7 @@ namespace dt {
         if (v == euf::null_theory_var) 
             return false;
         euf::enode* con = m_var_data[m_find.find(v)]->m_constructor;
-        CTRACE("dt", !con, display(tout) << ctx.bpp(n) << "\n";);
+        TRACE("dt", display(tout) << ctx.bpp(n) << " con: " << ctx.bpp(con) << "\n";);
         if (con->num_args() == 0)
             dep.insert(n, nullptr);
         for (enode* arg : euf::enode_args(con))
@@ -794,16 +794,15 @@ namespace dt {
     bool solver::include_func_interp(func_decl* f) const {
         if (!dt.is_accessor(f))
             return false;
-        func_decl* con = dt.get_accessor_constructor(f);
-        for (enode* app : ctx.get_egraph().enodes_of(f)) {
-            enode* arg = app->get_arg(0)->get_root();
-            if (is_constructor(arg) && arg->get_decl() != con) 
+        func_decl* con_decl = dt.get_accessor_constructor(f);
+        for (enode* app : ctx.get_egraph().enodes_of(f)) {   
+            enode* con = oc_get_cstor(app->get_arg(0));
+            if (con && is_constructor(con) && con->get_decl() != con_decl) 
                 return true;
         }
         return false; 
     }
 
-
     sat::literal solver::internalize(expr* e, bool sign, bool root) {
         if (!visit_rec(m, e, sign, root)) 
             return sat::null_literal;        
diff --git a/src/sat/smt/dt_solver.h b/src/sat/smt/dt_solver.h
index 51a7679fd..b2cbba63b 100644
--- a/src/sat/smt/dt_solver.h
+++ b/src/sat/smt/dt_solver.h
@@ -116,7 +116,7 @@ namespace dt {
 
         void pop_core(unsigned n) override;
 
-        enode * oc_get_cstor(enode * n);
+        enode * oc_get_cstor(enode * n) const;
         bool occurs_check(enode * n);
         bool occurs_check_enter(enode * n);
         void occurs_check_explain(enode * top, enode * root);