@include scut-vcenter-ib('.custom-selector') yields invalid result

[kamikat]

In SASS source file

.icon {
  @include scut-vcenter-ib('.icon-glyph');
}

compiles to

.icon:before {
  content: "";
  height: 100%;
  display: inline-block;
  vertical-align: middle;
  margin-right: -0.25em; }
.icon > ".icon-glyph" { /* <<< invalid selector */
  display: inline-block;
  vertical-align: middle; }