diff --git a/include/boost/smart_ptr/detail/yield_k.hpp b/include/boost/smart_ptr/detail/yield_k.hpp
index 2dabc9f..c3d0450 100644
--- a/include/boost/smart_ptr/detail/yield_k.hpp
+++ b/include/boost/smart_ptr/detail/yield_k.hpp
@@ -60,8 +60,12 @@ namespace detail
 {
 
 #if !defined( BOOST_USE_WINDOWS_H ) && !BOOST_PLAT_WINDOWS_RUNTIME
+#if BOOST_COMP_CLANG
+  extern "C" __declspec(dllimport) void __stdcall Sleep( unsigned long ms );
+#else
   extern "C" void __stdcall Sleep( unsigned long ms );
 #endif
+#endif
 
 inline void yield( unsigned k )
 {