diff --git a/src/api/c++/z3++.h b/src/api/c++/z3++.h
index 625964347..c99979355 100644
--- a/src/api/c++/z3++.h
+++ b/src/api/c++/z3++.h
@@ -497,6 +497,7 @@ namespace z3 {
         ast(context & c):object(c), m_ast(0) {}
         ast(context & c, Z3_ast n):object(c), m_ast(n) { Z3_inc_ref(ctx(), m_ast); }
         ast(ast const & s):object(s), m_ast(s.m_ast) { Z3_inc_ref(ctx(), m_ast); }
+        ast(ast && s) noexcept : object(std::forward<object>(s)), m_ast(s.m_ast) { s.m_ast = nullptr; }
         ~ast() { if (m_ast) Z3_dec_ref(*m_ctx, m_ast); }
         operator Z3_ast() const { return m_ast; }
         operator bool() const { return m_ast != 0; }
@@ -508,6 +509,12 @@ namespace z3 {
             m_ast = s.m_ast;
             return *this;
         }
+        ast & operator=(ast && s) noexcept {
+            object::operator=(std::forward<object>(s));
+            m_ast = s.m_ast;
+            s.m_ast = nullptr;
+            return *this;
+        }
         Z3_ast_kind kind() const { Z3_ast_kind r = Z3_get_ast_kind(ctx(), m_ast); check_error(); return r; }
         unsigned hash() const { unsigned r = Z3_get_ast_hash(ctx(), m_ast); check_error(); return r; }
         friend std::ostream & operator<<(std::ostream & out, ast const & n);