diff -r b91b558a9076 -r ef5d5d343e2a src/hotspot/share/runtime/objectMonitor.hpp
--- a/src/hotspot/share/runtime/objectMonitor.hpp	Fri Mar 16 08:26:53 2018 -0400
+++ b/src/hotspot/share/runtime/objectMonitor.hpp	Fri Mar 16 09:12:13 2018 -0400
@@ -31,6 +31,8 @@
 #include "runtime/park.hpp"
 #include "runtime/perfData.hpp"
 
+class ObjectMonitor;
+
 // ObjectWaiter serves as a "proxy" or surrogate thread.
 // TODO-FIXME: Eliminate ObjectWaiter and use the thread-specific
 // ParkEvent instead.  Beware, however, that the JVMTI code