diff --git a/src/package.json b/src/package.json
index 855940f25e7..ef317791f2d 100644
--- a/src/package.json
+++ b/src/package.json
@@ -3,7 +3,7 @@
   "dependencies": {
     "acorn": "5.1.1",
     "codemirror": "5.30.0",
-    "less": "2.7.2",
+    "less": "3.12.0",
     "preact": "8.2.1",
     "preact-test-utils": "0.1.3",
     "preact-compat": "adobe/preact-compat"