diff --git a/lib/server.js b/lib/server.js
index 31b5306e0..020b01f05 100644
--- a/lib/server.js
+++ b/lib/server.js
@@ -59,7 +59,7 @@ class Server extends KarmaEventEmitter {
     super()
     cliOptionsOrConfig = cliOptionsOrConfig || {}
     this.log = logger.create('karma-server')
-    done = helper.isFunction(done) ? done : process.exit
+    done = helper.isFunction(done) ? done : () => null
     this.loadErrors = []
 
     let config