diff --git a/src/Umbraco.Web.UI.Client/src/less/application/grid.less b/src/Umbraco.Web.UI.Client/src/less/application/grid.less
index e909d0376d..9d1ec8cd32 100644
--- a/src/Umbraco.Web.UI.Client/src/less/application/grid.less
+++ b/src/Umbraco.Web.UI.Client/src/less/application/grid.less
@@ -120,7 +120,7 @@ body {
 
 @media (max-width: 500px) {
     #search-form .form-search {
-        width: ~"calc(100% - 80px)"
+        width: ~"(calc(~'100%' - ~'80px'))";
     }
 }
 
diff --git a/src/Umbraco.Web.UI.Client/src/less/sections.less b/src/Umbraco.Web.UI.Client/src/less/sections.less
index 26abf4404f..c764280c8d 100644
--- a/src/Umbraco.Web.UI.Client/src/less/sections.less
+++ b/src/Umbraco.Web.UI.Client/src/less/sections.less
@@ -111,7 +111,7 @@ ul.sections li.help {
 	bottom: 0;
 	left: 0;
 	display: block;
-	width: ~"calc(100% - 5px)"; //subtract 4px orange border + 1px border-right for sections
+	width: ~"(calc(~'100%' - ~'5px'))"; //subtract 4px orange border + 1px border-right for sections
 }
 
 ul.sections li.help a {