diff --git a/doc/reference.qbk b/doc/reference.qbk
index e565c65b..dca80c7a 100644
--- a/doc/reference.qbk
+++ b/doc/reference.qbk
@@ -35354,7 +35354,7 @@ Destroy all user-defined handler objects owned by the service.
 [section:deadline_timer deadline_timer]
 
 [indexterm1 deadline_timer] 
-Typedef for the typical usage of timer. 
+Typedef for the typical usage of timer. Uses a UTC clock. 
 
 
   typedef basic_deadline_timer< boost::posix_time::ptime > deadline_timer;
diff --git a/include/boost/asio/deadline_timer.hpp b/include/boost/asio/deadline_timer.hpp
index a62a2ce1..0f9e28d1 100644
--- a/include/boost/asio/deadline_timer.hpp
+++ b/include/boost/asio/deadline_timer.hpp
@@ -28,7 +28,7 @@
 namespace boost {
 namespace asio {
 
-/// Typedef for the typical usage of timer.
+/// Typedef for the typical usage of timer. Uses a UTC clock.
 typedef basic_deadline_timer<boost::posix_time::ptime> deadline_timer;
 
 } // namespace asio