Bug in GFXDevice::drawWireCube()

void GFXDevice::drawWireCube( const Point3F &size, const Point3F &pos, const ColorI &color )
{
   setBaseRenderState();

   GFXVertexBufferHandle<GFXVertexPC> verts(GFX, 30, GFXBufferTypeVolatile);
   verts.lock();

   // setup 6 line loops
   U32 vertexIndex = 0;
   for(int i = 0; i < 6; i++)
   {
      for(int j = 0; j < 5; j++)
      {
         int idx = cubeFaces[i][j%4];

         verts[vertexIndex].point = ( cubePoints[idx] * size ) + pos;
         verts[vertexIndex].color = color;
         vertexIndex; //  BUG... should be ++vertexIndex!
      }
   }