diff --git a/lib/manager/npm/post-update/index.js b/lib/manager/npm/post-update/index.js
index 6734a858eb0cf547b8ba52fe3480780d9898dc73..840cc5e3dc31b74d4eb4a2aec0bbd0fe0d342f9e 100644
--- a/lib/manager/npm/post-update/index.js
+++ b/lib/manager/npm/post-update/index.js
@@ -189,6 +189,7 @@ async function writeExistingFiles(config, packageFiles) {
         upath.join(basedir, '.yarnrc'),
         packageFile.yarnrc
           .replace('--install.pure-lockfile true', '')
+          .replace('--install.frozen-lockfile true', '')
           .replace(/^yarn-path.*$/m, '')
       );
     }