PVS-Studio warning V599 for Synergy

class CKeyMap {
public:
  CKeyMap();
  ~CKeyMap();
  ....
  virtual void swap(CKeyMap&);
  virtual void addHalfDuplexModifier(KeyID key);
  virtual void finish();
  ....
};

class CMockKeyMap : public CKeyMap { .... };

CKeyMap* m_keyMapPtr;

CKeyState::~CKeyState()
{
  if (m_keyMapPtr)
    delete m_keyMapPtr;
}

This suspicious code was found in Synergy project by PVS-Studio static code analyzer.
Warning message is:
V599 The destructor was not declared as a virtual one, although the 'CKeyMap' class contains virtual functions. ckeystate.cpp 408

PVS-Studio is a static analyzer for detecting bugs in the source code of applications written in C, C++, C++11, C++/CX. Site: http://www.viva64.com/en/pvs-studio/