diff --git a/src/ast/rewriter/pb2bv_rewriter.cpp b/src/ast/rewriter/pb2bv_rewriter.cpp
index 8125a651a..0157ca9ff 100644
--- a/src/ast/rewriter/pb2bv_rewriter.cpp
+++ b/src/ast/rewriter/pb2bv_rewriter.cpp
@@ -610,7 +610,7 @@ struct pb2bv_rewriter::imp {
             m_keep_pb_constraints(false),
             m_pb_num_system(false),
             m_pb_totalizer(false),
-            m_min_arity(2)
+            m_min_arity(3)
         {}
 
         bool mk_app(bool full, func_decl * f, unsigned sz, expr * const* args, expr_ref & result) {
diff --git a/src/sat/ba_solver.cpp b/src/sat/ba_solver.cpp
index 412b81ccc..d265ada75 100644
--- a/src/sat/ba_solver.cpp
+++ b/src/sat/ba_solver.cpp
@@ -213,13 +213,13 @@ namespace sat {
         return true;
     }
 
-    // ----------------------------
+    // ----------------------------            
     // card
 
     bool ba_solver::init_watch(card& c) {
-        clear_watch(c);
         literal root = c.lit();
         if (root != null_literal && value(root) == l_false) {
+            clear_watch(c);
             c.negate();
             root.neg();
         }
@@ -240,6 +240,10 @@ namespace sat {
         for (unsigned i = 0; i < sz; ++i) {
             if (value(c[i]) != l_false) {
                 if (j != i) {
+                    if (c.is_watched() && j <= bound && i > bound) {
+                        unwatch_literal(c[j], c);
+                        watch_literal(c[i], c);
+                    }
                     c.swap(i, j);
                 }
                 ++j;
@@ -255,6 +259,7 @@ namespace sat {
         // j is the number of non-false, sz - j the number of false.
 
         if (j < bound) {
+            if (c.is_watched()) clear_watch(c);
             SASSERT(0 < bound && bound < sz);
             literal alit = c[j];
             
@@ -280,14 +285,19 @@ namespace sat {
             return false;
         }
         else {
+            if (c.is_watched()) return true;
+            clear_watch(c);
             for (unsigned i = 0; i <= bound; ++i) {
                 watch_literal(c[i], c);
             }
+            c.set_watch();
             return true;
         }
     }
 
     void ba_solver::clear_watch(card& c) {
+        if (c.is_clear()) return;
+        c.clear_watch();
         unsigned sz = std::min(c.k() + 1, c.size());
         for (unsigned i = 0; i < sz; ++i) {
             unwatch_literal(c[i], c);            
@@ -747,6 +757,7 @@ namespace sat {
     }
 
     void ba_solver::clear_watch(pb& p) {
+        p.clear_watch();
         for (unsigned i = 0; i < p.num_watch(); ++i) {
             unwatch_literal(p[i].second, p);          
         }  
@@ -896,6 +907,7 @@ namespace sat {
     // xr:
 
     void ba_solver::clear_watch(xr& x) {
+        x.clear_watch();
         unwatch_literal(x[0], x);
         unwatch_literal(x[1], x);         
         unwatch_literal(~x[0], x);
diff --git a/src/sat/ba_solver.h b/src/sat/ba_solver.h
index 6b6d10c38..390025d63 100644
--- a/src/sat/ba_solver.h
+++ b/src/sat/ba_solver.h
@@ -63,6 +63,7 @@ namespace sat {
             tag_t          m_tag;
             bool           m_removed;
             literal        m_lit;
+            literal        m_watch;
             unsigned       m_glue;
             unsigned       m_psm;
             unsigned       m_size;
@@ -70,7 +71,8 @@ namespace sat {
             bool           m_learned;
             unsigned       m_id;
         public:
-            constraint(tag_t t, unsigned id, literal l, unsigned sz, size_t osz): m_tag(t), m_removed(false), m_lit(l), m_glue(0), m_psm(0), m_size(sz), m_obj_size(osz), m_learned(false), m_id(id) {}
+            constraint(tag_t t, unsigned id, literal l, unsigned sz, size_t osz): 
+            m_tag(t), m_removed(false), m_lit(l), m_watch(null_literal), m_glue(0), m_psm(0), m_size(sz), m_obj_size(osz), m_learned(false), m_id(id) {}
             ext_constraint_idx index() const { return reinterpret_cast<ext_constraint_idx>(this); }
             unsigned id() const { return m_id; }
             tag_t tag() const { return m_tag; }
@@ -87,6 +89,10 @@ namespace sat {
             void set_psm(unsigned p) { m_psm = p; }
             void set_learned(bool f) { m_learned = f; }
             bool learned() const { return m_learned; }            
+            bool is_watched() const { return m_watch == m_lit && m_lit != null_literal; }
+            void set_watch() { m_watch = m_lit; }
+            void clear_watch() { m_watch = null_literal; }
+            bool is_clear() const { return m_watch == null_literal && m_lit != null_literal; }
 
             size_t obj_size() const { return m_obj_size; }
             card& to_card();