diff --git a/websocketpp/transport/asio/endpoint.hpp b/websocketpp/transport/asio/endpoint.hpp
index 536518ed91..476b39414a 100644
--- a/websocketpp/transport/asio/endpoint.hpp
+++ b/websocketpp/transport/asio/endpoint.hpp
@@ -83,7 +83,7 @@ public:
 	
 	~endpoint() {
 		// clean up our io_service if we were initialized with an internal one.
-		if (m_state != UNINITIALIZED && m_external_io_service) {
+		if (m_state != UNINITIALIZED && !m_external_io_service) {
 			delete m_io_service;
 		}
 	}