diff --git a/src/scss/_mixins-override.scss b/src/scss/_mixins-override.scss
index b1bfe75f05..66a7af085e 100644
--- a/src/scss/_mixins-override.scss
+++ b/src/scss/_mixins-override.scss
@@ -72,4 +72,11 @@
   $active-color: null
 ) {
   // Override bootstrap core
+}
+
+//
+// TODO: remove when https://github.com/twbs/bootstrap/pull/37425/ will be released
+//
+@function opaque($background, $foreground) {
+  @return mix(rgba($foreground, 1), $background, opacity($foreground) * 100%);
 }
\ No newline at end of file
diff --git a/src/scss/mixins/_functions.scss b/src/scss/mixins/_functions.scss
index e6b28bf065..baf19bd311 100644
--- a/src/scss/mixins/_functions.scss
+++ b/src/scss/mixins/_functions.scss
@@ -44,4 +44,5 @@
     @error "breakpoint `#{$name}` not found in `#{$breakpoints}`";
   }
   @return if($n > 1, nth($breakpoint-names, $n - 1), null);
-}
\ No newline at end of file
+}
+