diff --git a/json/tree.cpp b/json/tree.cpp
index 359728de..bb5ccbd1 100644
--- a/json/tree.cpp
+++ b/json/tree.cpp
@@ -299,6 +299,20 @@ json::tree::object::~object ()
     { ; }
 
 
+//-----------------------------------------------------------------------------
+std::unique_ptr<json::tree::node>
+json::tree::object::clone (void) const
+{
+    auto obj = std::make_unique<json::tree::object> ();
+
+    for (auto &i: *this)
+        obj->insert (i.first, i.second->clone ());
+
+    return std::move (obj);
+}
+
+
+//-----------------------------------------------------------------------------
 bool
 json::tree::object::operator ==(const json::tree::object &rhs) const {
     for (auto i = rhs.m_values.begin (), j = m_values.begin ();
@@ -402,6 +416,20 @@ json::tree::array::~array()
 }
 
 
+//-----------------------------------------------------------------------------
+std::unique_ptr<json::tree::node>
+json::tree::array::clone (void) const
+{
+    auto ret = std::make_unique<array> ();
+
+    for (const auto &i: *this)
+        ret->insert (i.clone ());
+
+    return std::move (ret);
+}
+
+
+//-----------------------------------------------------------------------------
 void
 json::tree::array::insert (unique_ptr<json::tree::node> &&_value)
 {
@@ -441,6 +469,14 @@ json::tree::array::write (std::ostream &os) const {
 //-----------------------------------------------------------------------------
 // String
 
+std::unique_ptr<json::tree::node>
+json::tree::string::clone (void) const
+{
+    return std::make_unique<json::tree::string> (m_value);
+}
+
+
+//-----------------------------------------------------------------------------
 std::ostream&
 json::tree::string::write (std::ostream &os) const {
     os << '"' << m_value << '"';
@@ -461,6 +497,14 @@ json::tree::string::operator ==(const char *rhs) const
 //-----------------------------------------------------------------------------
 // Number
 
+std::unique_ptr<json::tree::node>
+json::tree::number::clone (void) const
+{
+    return std::make_unique<json::tree::number> (m_value);
+}
+
+
+//-----------------------------------------------------------------------------
 std::ostream&
 json::tree::number::write (std::ostream &os) const {
     os << setprecision (numeric_limits<double>::digits10) << m_value;
@@ -476,6 +520,14 @@ json::tree::number::operator ==(const json::tree::number &rhs) const
 //-----------------------------------------------------------------------------
 // Boolean
 
+std::unique_ptr<json::tree::node>
+json::tree::boolean::clone (void) const
+{
+    return std::make_unique<json::tree::boolean> (m_value);
+}
+
+
+//-----------------------------------------------------------------------------
 std::ostream&
 json::tree::boolean::write (std::ostream &os) const {
     os << (m_value ? "true" : "false");
@@ -490,6 +542,14 @@ json::tree::boolean::operator ==(const json::tree::boolean &rhs) const
 //-----------------------------------------------------------------------------
 // Null
 
+std::unique_ptr<json::tree::node>
+json::tree::null::clone (void) const
+{
+    return std::make_unique<json::tree::null> ();
+}
+
+
+//-----------------------------------------------------------------------------
 std::ostream&
 json::tree::null::write (std::ostream &os) const {
     os << "null";
diff --git a/json/tree.hpp b/json/tree.hpp
index 8f5d8d81..4cabc495 100644
--- a/json/tree.hpp
+++ b/json/tree.hpp
@@ -52,6 +52,7 @@ namespace json { namespace tree {
     class node {
         public:
             virtual ~node () { ; }
+            virtual std::unique_ptr<node> clone (void) const = 0;
 
             virtual const object&  as_object  (void) const;
             virtual const array&   as_array   (void) const;
@@ -103,6 +104,7 @@ namespace json { namespace tree {
 
         public:
             virtual ~object ();
+            virtual std::unique_ptr<node> clone (void) const;
 
             virtual const object& as_object  (void) const { return *this; }
             virtual bool          is_object  (void) const { return  true; }
@@ -139,6 +141,7 @@ namespace json { namespace tree {
 
         public:
             virtual ~array();
+            virtual std::unique_ptr<node> clone (void) const;
 
             virtual const array&  as_array   (void) const { return *this; }
             virtual bool          is_array   (void) const { return  true; }
@@ -171,6 +174,7 @@ namespace json { namespace tree {
             explicit string (const std::string &_value): m_value (_value) { ; }
             explicit string (const char        *_value): m_value (_value) { ; }
             string (const char *_first, const char *_last): m_value (_first, _last) { ; }
+            virtual std::unique_ptr<node> clone (void) const;
 
             virtual const string& as_string  (void) const { return *this; }
             virtual bool          is_string  (void) const { return  true; }
@@ -197,6 +201,7 @@ namespace json { namespace tree {
             explicit number (double _value): m_value (_value) { ; }
             explicit number (int    _value): m_value (_value) { ; }
             explicit number (size_t _value): m_value (_value) { ; }
+            virtual std::unique_ptr<node> clone (void) const;
 
             virtual const number& as_number  (void) const { return *this; }
             virtual bool          is_number  (void) const { return  true; }
@@ -218,6 +223,7 @@ namespace json { namespace tree {
 
         public:
             explicit boolean (bool _value): m_value (_value) { ; }
+            virtual std::unique_ptr<node> clone (void) const;
 
             virtual const boolean& as_boolean (void) const { return *this; }
             virtual bool           is_boolean (void) const { return  true; }
@@ -235,6 +241,8 @@ namespace json { namespace tree {
     /// Represents a JSON null value.
     class null : public node {
         public:
+            virtual std::unique_ptr<node> clone (void) const;
+
             virtual bool operator==(const null&) const { return true; }
             virtual bool operator==(const node   &rhs) const
                 { return rhs == *this; }