diff --git a/src/share/vm/runtime/globals.hpp b/src/share/vm/runtime/globals.hpp
index c5d4a627b636895ad6bd4d79f56e3860feddb91b..05d8de1ff3eb305131f6747b85f236886c573ea8 100644
--- a/src/share/vm/runtime/globals.hpp
+++ b/src/share/vm/runtime/globals.hpp
@@ -1599,7 +1599,7 @@ class CommandLineFlags {
   develop(bool, CMSTraceThreadState, false,                                 \
           "Trace the CMS thread state (enable the trace_state() method)")   \
                                                                             \
-  product(bool, CMSClassUnloadingEnabled, false,                            \
+  product(bool, CMSClassUnloadingEnabled, true,                             \
           "Whether class unloading enabled when using CMS GC")              \
                                                                             \
   product(uintx, CMSClassUnloadingMaxInterval, 0,                           \