diff -r a6deb69743d4 -r 4cbfa5077d68 src/hotspot/os/windows/os_windows.cpp
--- a/src/hotspot/os/windows/os_windows.cpp	Mon Nov 25 12:32:07 2019 +0100
+++ b/src/hotspot/os/windows/os_windows.cpp	Mon Nov 25 12:32:40 2019 +0100
@@ -5236,7 +5236,7 @@
   // from the first park() call after an unpark() call which will help
   // shake out uses of park() and unpark() without condition variables.
 
-  if (Atomic::xchg(1, &_Event) >= 0) return;
+  if (Atomic::xchg(&_Event, 1) >= 0) return;
 
   ::SetEvent(_ParkHandle);
 }