--- old/src/os/windows/vm/semaphore_windows.hpp	2017-06-30 10:54:35.567469756 +0200
+++ new/src/os/windows/vm/semaphore_windows.hpp	2017-06-30 10:54:35.463465414 +0200
@@ -43,6 +43,8 @@
   void signal(uint count = 1);
 
   void wait();
+
+  bool trywait();
 };
 
 typedef WindowsSemaphore SemaphoreImpl;