diff --git a/Gruntfile.js b/Gruntfile.js
index d1b474c0..041ff2ac 100644
--- a/Gruntfile.js
+++ b/Gruntfile.js
@@ -90,6 +90,14 @@ module.exports = function (grunt) {
               order: 24
             },
 
+
+            // fix calc references
+            { // https://regex101.com/r/aZ8iI5/1
+              pattern: /calc\(unquote\("([^"]+)"\)\)/gi,
+              replacement: 'calc($1)',
+              order: 24
+            },
+
             // alert generic-variations (convert this one last - very broad search)
             { // Multi-line replacement - https://regex101.com/r/jB1uL1/1
               pattern: /.generic-variations\(unquote\(("([^"]+)?")\), (\$[\s\S]+?(?!\r|\n)), {$\n[\s\S]+}\);$\n/mg,
diff --git a/sass/_inputs.scss b/sass/_inputs.scss
index 10b8023f..893bb0d9 100644
--- a/sass/_inputs.scss
+++ b/sass/_inputs.scss
@@ -31,7 +31,7 @@ select[multiple].form-control {
   background-image: linear-gradient($primary, $primary), linear-gradient($input-underline-color, $input-underline-color);
   background-size: 0 2px, 100% 1px;
   background-repeat: no-repeat;
-  background-position: center bottom, center calc(unquote("100% - 1px"));
+  background-position: center bottom, center calc(100% - 1px);
   background-color: transparent;
   background-color: rgba(0,0,0,0);
   transition: background 0s ease-out;