diff --git a/react-00/chapter-4/Adding-Final/yarn.lock b/react-00/chapter-4/Adding-Final/yarn.lock
index 644810cb..9148d302 100644
--- a/react-00/chapter-4/Adding-Final/yarn.lock
+++ b/react-00/chapter-4/Adding-Final/yarn.lock
@@ -1539,9 +1539,9 @@ clap@^1.0.9:
     chalk "^1.1.3"
 
 clean-css@4.1.x:
-  version "4.1.9"
-  resolved "https://registry.yarnpkg.com/clean-css/-/clean-css-4.1.9.tgz#35cee8ae7687a49b98034f70de00c4edd3826301"
-  integrity sha1-Nc7ornaHpJuYA09w3gDE7dOCYwE=
+  version "4.1.11"
+  resolved "https://registry.yarnpkg.com/clean-css/-/clean-css-4.1.11.tgz#2ecdf145aba38f54740f26cefd0ff3e03e125d6a"
+  integrity sha1-Ls3xRaujj1R0DybO/Q/z4D4SXWo=
   dependencies:
     source-map "0.5.x"