diff --git a/src/sat/sat_drat.cpp b/src/sat/sat_drat.cpp
index 608728002..eea88bde7 100644
--- a/src/sat/sat_drat.cpp
+++ b/src/sat/sat_drat.cpp
@@ -332,10 +332,17 @@ namespace sat {
     }
 
     void drat::verify(unsigned n, literal const* c) {
-        if (m_check_unsat && !is_drup(n, c) && !is_drat(n, c)) {
+        if (!m_check_unsat) {
+            return;
+        }
+        for (unsigned i = 0; i < n; ++i) { 
+            declare(c[i]);
+        } 
+        if (!is_drup(n, c) && !is_drat(n, c)) {
             literal_vector lits(n, c);
             std::cout << "Verification of " << lits << " failed\n";
             s.display(std::cout);
+            SASSERT(false);
             exit(0);
             UNREACHABLE();
             //display(std::cout);
@@ -476,6 +483,10 @@ namespace sat {
                     literal lit = c[i];
                     if (lit != wc.m_l1 && lit != wc.m_l2 && value(lit) != l_false) {
                         wc.m_l2 = lit;
+						if (m_watches.size() <= (~lit).index())
+						{
+							IF_VERBOSE(0, verbose_stream() << m_watches.size() << " " << lit << " " << (~lit).index() << "\n");
+						}
                         m_watches[(~lit).index()].push_back(idx);
                         done = true;
                     } 
diff --git a/src/sat/sat_solver.cpp b/src/sat/sat_solver.cpp
index c9b535997..43adebb25 100644
--- a/src/sat/sat_solver.cpp
+++ b/src/sat/sat_solver.cpp
@@ -344,11 +344,11 @@ namespace sat {
 
     void solver::mk_bin_clause(literal l1, literal l2, bool learned) {
         if (find_binary_watch(get_wlist(~l1), ~l2)) {
-            assign_core(l1, 0, justification(l2));
+            assign_core(l1, 0, justification(l1));
             return;
         }
         if (find_binary_watch(get_wlist(~l2), ~l1)) {
-            assign_core(l2, 0, justification(l1));
+            assign_core(l2, 0, justification(l2));
             return;
         }
         watched* w0 = find_binary_watch(get_wlist(~l1), l2);
diff --git a/src/tactic/goal.cpp b/src/tactic/goal.cpp
index dfe63e29a..6444cbc05 100644
--- a/src/tactic/goal.cpp
+++ b/src/tactic/goal.cpp
@@ -434,7 +434,8 @@ void goal::display_ll(std::ostream & out) const {
    \brief Assumes that the formula is already in CNF.
 */
 void goal::display_dimacs(std::ostream & out) const {
-    obj_map<expr, unsigned> expr2var;
+    unsigned_vector expr2var;
+    ptr_vector<expr> exprs;
     unsigned num_vars = 0;
     unsigned num_cls  = size();
     for (unsigned i = 0; i < num_cls; i++) {
@@ -453,10 +454,11 @@ void goal::display_dimacs(std::ostream & out) const {
             expr * l = lits[j];
             if (m().is_not(l))
                 l = to_app(l)->get_arg(0);
-            if (expr2var.contains(l))
-                continue;
-            num_vars++;
-            expr2var.insert(l, num_vars);
+            if (expr2var.get(l->get_id(), UINT_MAX) == UINT_MAX) {
+                num_vars++;
+                expr2var.setx(l->get_id(), num_vars, UINT_MAX);
+                exprs.setx(l->get_id(), l, nullptr);
+            }
         }
     }
     out << "p cnf " << num_vars << " " << num_cls << "\n";
@@ -478,17 +480,16 @@ void goal::display_dimacs(std::ostream & out) const {
                 out << "-";
                 l = to_app(l)->get_arg(0);
             }
-            unsigned id = UINT_MAX;
-            expr2var.find(l, id);
+            unsigned id = expr2var[l->get_id()];
             SASSERT(id != UINT_MAX);
             out << id << " ";
         }
         out << "0\n";
     }
-    for (auto const& kv : expr2var) {
-        expr* key = kv.m_key;
-        if (is_app(key)) 
-            out << "c " << kv.m_value << " " << to_app(key)->get_decl()->get_name() << "\n";
+    for (expr* e : exprs) {
+        if (e && is_app(e)) {
+            out << "c " << expr2var[e->get_id()] << " " << to_app(e)->get_decl()->get_name() << "\n";
+        }
     }
 }