diff --git a/scss/mixins/_buttons.scss b/scss/mixins/_buttons.scss
index 1e01de867d..f7ec5764e7 100644
--- a/scss/mixins/_buttons.scss
+++ b/scss/mixins/_buttons.scss
@@ -3,16 +3,12 @@
 // Easily pump out default styles, as well as :hover, :focus, :active,
 // and disabled options for all buttons
 
-@mixin button-variant($background, $border) {
-  $active-background: darken($background, 7.5%);
-  $active-border: darken($border, 10%);
-
+@mixin button-variant($background, $border, $active-background: darken($background, 7.5%), $active-border: darken($border, 10%)) {
   @include color-yiq($background);
   background-color: $background;
   border-color: $border;
   @include box-shadow($btn-box-shadow);
 
-  // Hover and focus styles are shared
   &:hover {
     @include color-yiq($background);
     background-color: $active-background;