diff --git a/include/boost/thread/win32/thread_primitives.hpp b/include/boost/thread/win32/thread_primitives.hpp
index 5e378f7..6144621 100644
--- a/include/boost/thread/win32/thread_primitives.hpp
+++ b/include/boost/thread/win32/thread_primitives.hpp
@@ -70,7 +70,7 @@ namespace boost
     {
         namespace win32
         {
-            namespace detail { typedef ticks_type (WINAPI *gettickcount64_t)(); }
+            namespace detail { typedef ticks_type (__stdcall *gettickcount64_t)(); }
             extern BOOST_THREAD_DECL boost::detail::win32::detail::gettickcount64_t gettickcount64;
 
             enum event_type
