diff --git a/src/poller.cc b/src/poller.cc
index f07e1d4b..429e9055 100644
--- a/src/poller.cc
+++ b/src/poller.cc
@@ -245,7 +245,7 @@ void Poller::RemoveEventer(Eventer* eventer) {
 }
 
 void Poller::GetActiveEventer(int event_amount,
-                              const PollEventList active_events,
+                              const PollEventList& active_events,
                               EventerList* active_eventers) const {
   LockGuard lock_guard(event_lock_);
   for (auto itr = active_events.cbegin();
diff --git a/src/poller.h b/src/poller.h
index 6faf85c7..e16c4269 100644
--- a/src/poller.h
+++ b/src/poller.h
@@ -102,7 +102,7 @@ class Poller : NonCopyableMovable {
   typedef std::map<int, Eventer*> EventerMap;
   typedef std::vector<struct pollfd> PollEventList;
 
-  void GetActiveEventer(int event_amount, const PollEventList active_events,
+  void GetActiveEventer(int event_amount, const PollEventList& active_events,
                         EventerList* active_eventers) const;
 
   // Map for all file descriptors mapping to their corresponding "Eventer"s