diff --git a/src/assets/font-awesome/less/core.less b/src/assets/font-awesome/less/core.less
index 1ef7e2235..7a0e76288 100644
--- a/src/assets/font-awesome/less/core.less
+++ b/src/assets/font-awesome/less/core.less
@@ -16,7 +16,7 @@
 /* makes the font 33% larger relative to the icon container */
 .icon-large:before {
   vertical-align: -10%;
-  font-size: 4/3em;
+  font-size: (4em / 3);
 }
 
 /* makes sure icons active on rollover in links */
@@ -32,11 +32,11 @@ a {
 [class*=" icon-"] {
   &.icon-fixed-width {
     display: inline-block;
-    width: 16/14em;
+    width: (16em / 14);
     text-align: right;
-    padding-right: 4/14em;
+    padding-right: (4em / 14);
     &.icon-large {
-      width: 20/14em;
+      width: (20em / 14);
     }
   }
 }
diff --git a/src/assets/font-awesome/less/font-awesome-ie7.less b/src/assets/font-awesome/less/font-awesome-ie7.less
index 2822fdee6..57c946ac3 100644
--- a/src/assets/font-awesome/less/font-awesome-ie7.less
+++ b/src/assets/font-awesome/less/font-awesome-ie7.less
@@ -3,7 +3,7 @@
 {% include license-code.less %}
 
 .icon-large {
-  font-size: 4/3em;
+  font-size: (4em / 3);
   margin-top: -4px;
   padding-top: 3px;
   margin-bottom: -4px;
diff --git a/src/assets/font-awesome/less/mixins.less b/src/assets/font-awesome/less/mixins.less
index f7fdda590..0988f223c 100644
--- a/src/assets/font-awesome/less/mixins.less
+++ b/src/assets/font-awesome/less/mixins.less
@@ -42,7 +42,7 @@
     }
     .icon-stack-base {
       font-size: @base-font-size;
-      *line-height: @height / @base-font-size;
+      *line-height: (@height / @base-font-size);
     }
   }
 }
diff --git a/src/assets/font-awesome/less/variables.less b/src/assets/font-awesome/less/variables.less
index 4d5271896..3cb4b616a 100644
--- a/src/assets/font-awesome/less/variables.less
+++ b/src/assets/font-awesome/less/variables.less
@@ -10,7 +10,7 @@
 @iconMuted:          #eee;
 @iconLight:          #fff;
 @iconDark:           #333;
-@icons-li-width:     30/14em;
+@icons-li-width:     (30em / 14);
 
 {% for icon in icons %}
   @{{ icon.id }}: "\{{ icon.unicode }}";