jQuery custom scroll causes flicker

I'm using this jQuery custom content scroller and it causes the scrollable section to flicker.

• On clicking another random button it continuously flickers
• If I take no action, it flickers on every few seconds interval

The code used:

$('.custom-scrollbar').mCustomScrollbar({
  scrollInertia: 0,
  alwaysShowScrollbar: 1, // adding / removing this causes no difference
  scrollbarPosition: 'outside'
});

Attached a gif to demonstrate the issue: http://gyazo.com/9ea9d558f2630c74a157c70a367d1868

If it helps anyone: As a fix, I just added a 1px padding for the container; no more flickering.