diff --git a/src/ast/converters/expr_inverter.cpp b/src/ast/converters/expr_inverter.cpp
index 41a60ccd5..abf3125c6 100644
--- a/src/ast/converters/expr_inverter.cpp
+++ b/src/ast/converters/expr_inverter.cpp
@@ -81,7 +81,7 @@ public:
      *
      */
 
-    bool operator()(func_decl* f, unsigned num, expr* const* args, expr_ref& r, proof_ref& pr) override {
+    bool operator()(func_decl* f, unsigned num, expr* const* args, expr_ref& r) override {
         SASSERT(f->get_family_id() == m.get_basic_family_id());
         switch (f->get_decl_kind()) {
         case OP_ITE:
@@ -233,7 +233,7 @@ public:
     }
 
 
-    bool operator()(func_decl* f, unsigned num, expr* const* args, expr_ref& r, proof_ref& pr) override {
+    bool operator()(func_decl* f, unsigned num, expr* const* args, expr_ref& r) override {
         SASSERT(f->get_family_id() == a.get_family_id());
         switch (f->get_decl_kind()) {
         case OP_ADD:
@@ -531,7 +531,7 @@ class bv_expr_inverter : public iexpr_inverter {
      * y := 0
      *
      */
-    bool operator()(func_decl* f, unsigned num, expr* const* args, expr_ref& r, proof_ref& pr) override {
+    bool operator()(func_decl* f, unsigned num, expr* const* args, expr_ref& r) override {
         SASSERT(f->get_family_id() == bv.get_family_id());
         switch (f->get_decl_kind()) {
         case OP_BADD:
@@ -611,7 +611,7 @@ public:
 
     family_id get_fid() const override { return a.get_family_id(); }
 
-    bool operator()(func_decl* f, unsigned num, expr* const* args, expr_ref& r, proof_ref& pr) override {
+    bool operator()(func_decl* f, unsigned num, expr* const* args, expr_ref& r) override {
         SASSERT(f->get_family_id() == a.get_family_id());
         switch (f->get_decl_kind()) {
         case OP_SELECT:
@@ -679,7 +679,7 @@ public:
      *   head(x) -> fresh
      *   x := cons(fresh, arb)
      */
-    bool operator()(func_decl* f, unsigned num, expr* const* args, expr_ref& r, proof_ref& pr) override {
+    bool operator()(func_decl* f, unsigned num, expr* const* args, expr_ref& r) override {
         if (dt.is_accessor(f)) {
             SASSERT(num == 1);
             if (uncnstr(args[0])) {
@@ -799,7 +799,7 @@ expr_inverter::expr_inverter(ast_manager& m): iexpr_inverter(m) {
 }
 
 
-bool expr_inverter::operator()(func_decl* f, unsigned num, expr* const* args, expr_ref& new_expr, proof_ref& pr) {
+bool expr_inverter::operator()(func_decl* f, unsigned num, expr* const* args, expr_ref& new_expr) {
     if (num == 0)
         return false;
             
@@ -812,7 +812,7 @@ bool expr_inverter::operator()(func_decl* f, unsigned num, expr* const* args, ex
         return false;
 
     auto* p = m_inverters.get(fid, nullptr);
-    return p && (*p)(f, num, args, new_expr, pr);       
+    return p && (*p)(f, num, args, new_expr);       
 }
 
 bool expr_inverter::mk_diff(expr* t, expr_ref& r) {
diff --git a/src/ast/converters/expr_inverter.h b/src/ast/converters/expr_inverter.h
index 60540aff3..e57820f35 100644
--- a/src/ast/converters/expr_inverter.h
+++ b/src/ast/converters/expr_inverter.h
@@ -40,7 +40,7 @@ public:
     virtual void set_model_converter(generic_model_converter* mc) { m_mc = mc; }
     virtual void set_produce_proofs(bool p) { m_produce_proofs = true; }
     
-    virtual bool operator()(func_decl* f, unsigned n, expr* const* args, expr_ref& new_expr, proof_ref& pr) = 0;
+    virtual bool operator()(func_decl* f, unsigned n, expr* const* args, expr_ref& new_expr) = 0;
     virtual bool mk_diff(expr* t, expr_ref& r) = 0;
     virtual family_id get_fid() const = 0;
 };
@@ -51,7 +51,7 @@ class expr_inverter : public iexpr_inverter {
 public:
     expr_inverter(ast_manager& m);
     ~expr_inverter() override;
-    bool operator()(func_decl* f, unsigned n, expr* const* args, expr_ref& new_expr, proof_ref& pr) override;
+    bool operator()(func_decl* f, unsigned n, expr* const* args, expr_ref& new_expr) override;
     bool mk_diff(expr* t, expr_ref& r) override;
     void set_is_var(std::function<bool(expr*)>& is_var) override; 
     void set_model_converter(generic_model_converter* mc) override;
diff --git a/src/ast/simplifiers/elim_unconstrained.cpp b/src/ast/simplifiers/elim_unconstrained.cpp
index 982a3c7dc..9c4badd01 100644
--- a/src/ast/simplifiers/elim_unconstrained.cpp
+++ b/src/ast/simplifiers/elim_unconstrained.cpp
@@ -63,7 +63,6 @@ void elim_unconstrained::eliminate() {
 
     while (!m_heap.empty()) {
         expr_ref r(m);
-        proof_ref pr(m);
         int v = m_heap.erase_min();
         node& n = get_node(v);
         if (n.m_refcount == 0)
@@ -85,7 +84,7 @@ void elim_unconstrained::eliminate() {
         unsigned sz = m_args.size();
         for (expr* arg : *to_app(t))
             m_args.push_back(reconstruct_term(get_node(arg)));
-        bool inverted = m_inverter(t->get_decl(), to_app(t)->get_num_args(), m_args.data() + sz, r, pr);
+        bool inverted = m_inverter(t->get_decl(), to_app(t)->get_num_args(), m_args.data() + sz, r);
         n.m_refcount = 0;
         m_args.shrink(sz);
         if (!inverted) {
@@ -114,7 +113,6 @@ void elim_unconstrained::eliminate() {
 
         IF_VERBOSE(11, verbose_stream() << mk_bounded_pp(get_node(v).m_orig, m) << " " << mk_bounded_pp(t, m) << " -> " << r << " " << get_node(e).m_refcount << "\n";);
 
-        SASSERT(!pr && "not implemented to add proofs\n");
     }
 }