diff --git a/lib/less/parser.js b/lib/less/parser.js
index 7670d6df3..bcb66a48a 100644
--- a/lib/less/parser.js
+++ b/lib/less/parser.js
@@ -630,7 +630,7 @@ less.Parser = function Parser(env) {
                     var value, c = input.charCodeAt(i);
                     if ((c > 57 || c < 45) || c === 47) return;
 
-                    if (value = $(/^(-?\d*\.?\d+)(px|%|em|pc|ex|in|deg|s|ms|pt|cm|mm|rad|grad|turn)?/)) {
+                    if (value = $(/^(-?\d*\.?\d+)(px|%|em|rem|pc|ex|in|deg|s|ms|pt|cm|mm|rad|grad|turn)?/)) {
                         return new(tree.Dimension)(value[1], value[2]);
                     }
                 },
diff --git a/test/css/operations.css b/test/css/operations.css
index 30a941b4f..fb9e0aff7 100644
--- a/test/css/operations.css
+++ b/test/css/operations.css
@@ -26,6 +26,9 @@
 .shorthands {
   padding: -1px 2px 0 -4px;
 }
+.rem-dimensions {
+  font-size: 5.5rem;
+}
 .colors {
   color: #123;
   border-color: #334455;
diff --git a/test/less/operations.less b/test/less/operations.less
index e7c974b34..46b0aa393 100644
--- a/test/less/operations.less
+++ b/test/less/operations.less
@@ -36,6 +36,10 @@
   padding: -1px 2px 0 -4px; //
 }
 
+.rem-dimensions {
+  font-size: 20rem / 5 + 1.5rem; // 5.5rem
+}
+
 .colors {
   color: #123; // #112233
   border-color: #234 + #111111; // #334455