diff --git a/websocketpp/endpoint.hpp b/websocketpp/endpoint.hpp
index c124b1d9a..fd9927a99 100644
--- a/websocketpp/endpoint.hpp
+++ b/websocketpp/endpoint.hpp
@@ -113,7 +113,7 @@ class endpoint : public config::transport_type, public config::endpoint_base {
 
     #ifdef _WEBSOCKETPP_DEFAULT_DELETE_FUNCTIONS_
         // no copy constructor because endpoints are not copyable
-        endpoint(endpoint &) = delete;
+        endpoint(const endpoint &) = delete;
     
         // no copy assignment operator because endpoints are not copyable
         endpoint & operator=(endpoint const &) = delete;