Input groups and dropdown-toggle - can't do without crutches?

Question

Bootstrap

Question for the bootstrap experts.
When grouping buttons with an input field, a button with the dropdown-toggle class has extra rounded right corners.
codepen.io/anon/pen/bVrgMp
Is it possible to fix this without crutches, in the form of my own css code?

Answer 1

.input-group-btn .btn{
  border-radius:0;
}