diff --git a/packages/@vue/cli-service/bin/vue-cli-service.js b/packages/@vue/cli-service/bin/vue-cli-service.js
index 0bed6ac2eb..a763f4e9d9 100755
--- a/packages/@vue/cli-service/bin/vue-cli-service.js
+++ b/packages/@vue/cli-service/bin/vue-cli-service.js
@@ -10,6 +10,7 @@ if (!semver.satisfies(process.version, requiredVersion)) {
   )
   process.exit(1)
 }
+process.env.VUE_CLI_MAIN_PROCESS_PID = process.pid
 
 const Service = require('../lib/Service')
 const service = new Service(process.env.VUE_CLI_CONTEXT || process.cwd())
diff --git a/packages/@vue/cli-service/lib/Service.js b/packages/@vue/cli-service/lib/Service.js
index 28a914d49e..d7bd9cfec0 100644
--- a/packages/@vue/cli-service/lib/Service.js
+++ b/packages/@vue/cli-service/lib/Service.js
@@ -292,7 +292,9 @@ module.exports = class Service {
       }
 
       entryFiles = entryFiles.map(file => path.resolve(this.context, file))
-      process.env.VUE_CLI_ENTRY_FILES = JSON.stringify(entryFiles)
+      if (process.env.VUE_CLI_MAIN_PROCESS_PID === process.pid) {
+        process.env.VUE_CLI_ENTRY_FILES = JSON.stringify(entryFiles)
+      }
     }
 
     return config