diff --git a/lib/webpack/createClientConfig.js b/lib/webpack/createClientConfig.js
index b09e2fd40e..8c27663301 100644
--- a/lib/webpack/createClientConfig.js
+++ b/lib/webpack/createClientConfig.js
@@ -45,7 +45,8 @@ module.exports = function createClientConfig (options, cliOptions) {
         canPrint: false,
         cssProcessorOptions: {
           safe: true,
-          autoprefixer: { disable: true }
+          autoprefixer: { disable: true },
+          mergeLonghand: false
         }
       }])
   }