diff --git a/src/emu/ioport.cpp b/src/emu/ioport.cpp
index 5fb28cc4ca6..50b27db4779 100644
--- a/src/emu/ioport.cpp
+++ b/src/emu/ioport.cpp
@@ -744,7 +744,7 @@ digital_joystick::digital_joystick(int player, int number)
 digital_joystick::direction_t digital_joystick::add_axis(ioport_field &field)
 {
 	direction_t direction = direction_t((field.type() - (IPT_DIGITAL_JOYSTICK_FIRST + 1)) % 4);
-	m_field[direction].append(field);
+	m_field[direction].append(*global_alloc(simple_list_wrapper<ioport_field>(&field)));
 	return direction;
 }
 
@@ -764,10 +764,10 @@ void digital_joystick::frame_update()
 	// read all the associated ports
 	running_machine *machine = NULL;
 	for (direction_t direction = JOYDIR_UP; direction < JOYDIR_COUNT; ++direction)
-		for (const ioport_field *i = m_field[direction].first(); i != NULL; i = i->next())
+		for (const simple_list_wrapper<ioport_field> *i = m_field[direction].first(); i != NULL; i = i->next())
 		{
-			machine = &i->machine();
-			if (machine->input().seq_pressed(i->seq(SEQ_TYPE_STANDARD)))
+			machine = &i->object()->machine();
+			if (machine->input().seq_pressed(i->object()->seq(SEQ_TYPE_STANDARD)))
 				m_current |= 1 << direction;
 		}
 
diff --git a/src/emu/ioport.h b/src/emu/ioport.h
index 908e8a0ef2a..5eeedb9a792 100644
--- a/src/emu/ioport.h
+++ b/src/emu/ioport.h
@@ -792,7 +792,7 @@ private:
 	digital_joystick *          m_next;                                         // next joystick in the list
 	int                         m_player;                                       // player number represented
 	int                         m_number;                                       // joystick number represented
-	simple_list<ioport_field> m_field[JOYDIR_COUNT];  // potential input fields for each direction
+	simple_list<simple_list_wrapper<ioport_field> > m_field[JOYDIR_COUNT];  // potential input fields for each direction
 	UINT8                       m_current;                                      // current value
 	UINT8                       m_current4way;                                  // current 4-way value
 	UINT8                       m_previous;                                     // previous value
diff --git a/src/lib/util/coretmpl.h b/src/lib/util/coretmpl.h
index f312b078a87..60c4e5f059e 100644
--- a/src/lib/util/coretmpl.h
+++ b/src/lib/util/coretmpl.h
@@ -277,6 +277,40 @@ private:
 	int             m_count;        // number of objects in the list
 };
 
+
+// ======================> simple_list_wrapper
+
+// a simple_list_wrapper wraps an existing object with a next pointer so it
+// can live in a simple_list without requiring the object to have a next
+// pointer
+template<class _ObjectType>
+class simple_list_wrapper
+{
+public:
+	template<class U> friend class simple_list;
+
+	// construction/destruction
+	simple_list_wrapper(_ObjectType *object)
+		: m_next(NULL),
+			m_object(object) { }
+
+	// operators
+	operator _ObjectType *() { return m_object; }
+	operator _ObjectType *() const { return m_object; }
+	_ObjectType *operator *() { return m_object; }
+	_ObjectType *operator *() const { return m_object; }
+
+	// getters
+	simple_list_wrapper *next() const { return m_next; }
+	_ObjectType *object() const { return m_object; }
+
+private:
+	// internal state
+	simple_list_wrapper *   m_next;
+	_ObjectType *           m_object;
+};
+
+
 // ======================> fixed_allocator
 
 // a fixed_allocator is a simple class that maintains a free pool of objects