diff --git a/src/port.h b/src/port.h
index 0a558fd..57d89df 100644
--- a/src/port.h
+++ b/src/port.h
@@ -65,6 +65,8 @@ struct Client : Base
 	PortGroupList m_groups;
 	PortList      m_ports;
 
+	virtual ~Client() { }
+
 	virtual ConnectionMode ConnectedTo(Port *port);
 	virtual ConnectionMode ConnectedTo(PortGroup *group);
 	virtual ConnectionMode ConnectedTo(Client *client);
@@ -76,6 +78,8 @@ struct PortGroup : Base
 {
 	PortList      m_ports;
 
+	virtual ~PortGroup() { }
+
 	virtual ConnectionMode ConnectedTo(Port *port);
 	virtual ConnectionMode ConnectedTo(PortGroup *group);
 	virtual ConnectionMode ConnectedTo(Client *client);
@@ -91,6 +95,8 @@ struct Port : Base
 	PortList     m_connections;
 	std::string  m_real_name;
 
+	virtual ~Port() { }
+
 	virtual ConnectionMode ConnectedTo(Port *port);
 	virtual ConnectionMode ConnectedTo(PortGroup *group);
 	virtual ConnectionMode ConnectedTo(Client *client);