diff --git a/yarn.lock b/yarn.lock
index d9d942497..a1b497321 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -833,13 +833,6 @@ class-utils@^0.3.5:
     isobject "^3.0.0"
     static-extend "^0.1.1"
 
-clean-css@^4.2.3:
-  version "4.2.3"
-  resolved "https://registry.npmjs.org/clean-css/-/clean-css-4.2.3.tgz#507b5de7d97b48ee53d84adb0160ff6216380f78"
-  integrity sha512-VcMWDN54ZN/DS+g58HYL5/n4Zrqe8vHJpGA8KdgUXFU4fuP/aHNw8eld9SyEIyabIMJX/0RaY/fplOo5hYLSFA==
-  dependencies:
-    source-map "~0.6.0"
-
 cliui@^2.1.0:
   version "2.1.0"
   resolved "https://registry.npmjs.org/cliui/-/cliui-2.1.0.tgz#4b475760ff80264c762c3a1719032e91c7fea0d1"
@@ -3572,7 +3565,7 @@ source-map@^0.5.0, source-map@^0.5.3, source-map@^0.5.6, source-map@~0.5.1:
   resolved "https://registry.npmjs.org/source-map/-/source-map-0.5.7.tgz#8a039d2d1021d22d1ea14c80d8ea468ba2ef3fcc"
   integrity sha1-igOdLRAh0i0eoUyA2OpGi6LvP8w=
 
-source-map@^0.6.0, source-map@^0.6.1, source-map@~0.6.0, source-map@~0.6.1:
+source-map@^0.6.0, source-map@^0.6.1, source-map@~0.6.1:
   version "0.6.1"
   resolved "https://registry.npmjs.org/source-map/-/source-map-0.6.1.tgz#74722af32e9614e9c287a8d0bbde48b5e2f1a263"
   integrity sha512-UjgapumWlbMhkBgzT7Ykc5YXUT46F0iKu8SGXq0bcwP5dz/h0Plj6enJqjz1Zbq2l5WaqYnrVbwWOWMyF3F47g==