--- old/src/hotspot/cpu/arm/globals_arm.hpp	2019-11-04 14:57:16.000000000 -0500
+++ new/src/hotspot/cpu/arm/globals_arm.hpp	2019-11-04 14:57:16.000000000 -0500
@@ -74,6 +74,10 @@
 define_pd_global(intx, InitArrayShortSize, 8*BytesPerLong);
 
 define_pd_global(bool, ThreadLocalHandshakes, false);
+// ObjectMonitor ref_count not implemented in C2 fast_lock() or
+// fast_unlock() so use a handshake for safety.
+// Will use a safepoint instead of a handshake on this platform.
+define_pd_global(bool, HandshakeAfterDeflateIdleMonitors, true);
 
 #define ARCH_FLAGS(develop, \
                    product, \