PVS-Studio warning V610 for Source SDK

inline void SetStyleType( int w, int h, int type )
{
  Assert( type < NUM_EDGE_STYLES );
  Assert( type >= 0 );
  // Clear old value
  m_nPanelBits[ w ][ h ] &= ( ~0x03 << 2 );
  // Insert new value
  m_nPanelBits[ w ][ h ] |= ( type << 2 );
}

This suspicious code was found in Source SDK project by PVS-Studio static code analyzer.
Warning message is:
V610 Undefined behavior. Check the shift operator '<<. The left operand '~0x03' is negative. Client (HL2) c_func_breakablesurf.cpp 157

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