--- old/src/hotspot/cpu/arm/globals_arm.hpp	2020-02-03 17:38:40.000000000 -0500
+++ new/src/hotspot/cpu/arm/globals_arm.hpp	2020-02-03 17:38:40.000000000 -0500
@@ -70,6 +70,11 @@
 
 define_pd_global(intx, InitArrayShortSize, 8*BytesPerLong);
 
+// 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, \
                    diagnostic, \