diff --git a/include/boost/smart_ptr/detail/yield_k.hpp b/include/boost/smart_ptr/detail/yield_k.hpp
index 9f4496b..2dabc9f 100644
--- a/include/boost/smart_ptr/detail/yield_k.hpp
+++ b/include/boost/smart_ptr/detail/yield_k.hpp
@@ -98,7 +98,13 @@ inline void yield( unsigned k )
 
 #elif defined( BOOST_HAS_PTHREADS )
 
+#ifndef _AIX
 #include <sched.h>
+#else
+   // AIX's sched.h defines ::var which sometimes conflicts with Lambda's var
+       extern "C" int sched_yield(void);
+#endif
+
 #include <time.h>
 
 namespace boost