diff --git a/include/boost/thread/win32/thread_data.hpp b/include/boost/thread/win32/thread_data.hpp
index 1a6a1e03..023c95b4 100644
--- a/include/boost/thread/win32/thread_data.hpp
+++ b/include/boost/thread/win32/thread_data.hpp
@@ -144,6 +144,11 @@ namespace boost
                 start(0),milliseconds(~uintmax_t(0)),relative(true)
             {}
         };
+
+        unsigned long pin_to_zero(long value)
+        {
+            return (value<0)?0u:(unsigned long)value;
+        }
     }
 
     namespace this_thread
@@ -163,7 +168,7 @@ namespace boost
         template<typename TimeDuration>
         inline void sleep(TimeDuration const& rel_time)
         {
-            interruptible_wait(static_cast<unsigned long>(rel_time.total_milliseconds()));
+            interruptible_wait(detail::pin_to_zero(rel_time.total_milliseconds()));
         }
         inline void sleep(system_time const& abs_time)
         {