diff --git a/src/port.c b/src/port.c
index 160b3e4..8c6f3e7 100644
--- a/src/port.c
+++ b/src/port.c
@@ -38,6 +38,7 @@ ep_port_t* ep_port_new(HANDLE iocp) {
   queue_init(&port_info->update_queue);
   tree_init(&port_info->sock_tree);
   reflock_tree_node_init(&port_info->handle_tree_node);
+  InitializeCriticalSection(&port_info->lock);
 
   return port_info;
 }
@@ -77,6 +78,8 @@ int ep_port_delete(ep_port_t* port_info) {
       poll_group_allocator_delete(pga);
   }
 
+  DeleteCriticalSection(&port_info->lock);
+
   _ep_port_free(port_info);
 
   return 0;
diff --git a/src/port.h b/src/port.h
index b14730f..cb06173 100644
--- a/src/port.h
+++ b/src/port.h
@@ -23,6 +23,7 @@ typedef struct ep_port {
   tree_t sock_tree;
   queue_t update_queue;
   reflock_tree_node_t handle_tree_node;
+  CRITICAL_SECTION lock;
 } ep_port_t;
 
 EPOLL_INTERNAL ep_port_t* ep_port_new(HANDLE iocp);