diff --git a/packages/@vuepress/core/lib/build.js b/packages/@vuepress/core/lib/build.js
index f8b362944c..0b96ff0fe3 100644
--- a/packages/@vuepress/core/lib/build.js
+++ b/packages/@vuepress/core/lib/build.js
@@ -83,7 +83,7 @@ module.exports = async function build (sourceDir, cliOptions = {}) {
   const relativeDir = path.relative(cwd, outDir)
   logger.success(`Generated static files in ${chalk.cyan(relativeDir)}.`)
   const { duration } = performance.stop()
-  logger.debug(`It took a total of ${duration}ms to run the ${chalk.cyan('vuepress build')}.`)
+  logger.debug(`It took a total of ${chalk.cyan(`${duration}ms`)} to run the ${chalk.cyan('vuepress build')}.`)
   console.log()
 
   // --- helpers ---
diff --git a/packages/@vuepress/core/lib/webpack/DevLogPlugin.js b/packages/@vuepress/core/lib/webpack/DevLogPlugin.js
index ec99352b3a..2bf57444bf 100644
--- a/packages/@vuepress/core/lib/webpack/DevLogPlugin.js
+++ b/packages/@vuepress/core/lib/webpack/DevLogPlugin.js
@@ -37,7 +37,7 @@ module.exports = class DevLogPlugin {
         isFirst = false
         console.log(`${chalk.gray('>')} VuePress dev server listening at ${chalk.cyan(displayUrl)}`)
         const { duration } = performance.stop()
-        logger.debug(`It took a total of ${duration}ms to run the ${chalk.cyan('vuepress dev')} for the first time.`)
+        logger.debug(`It took a total of ${chalk.cyan(`${duration}ms`)} to run the ${chalk.cyan('vuepress dev')} for the first time.`)
       }
     })
     compiler.hooks.invalid.tap('vuepress-log', clearScreen)