diff --git a/hotspot/src/share/vm/gc_implementation/concurrentMarkSweep/concurrentMarkSweepGeneration.cpp b/hotspot/src/share/vm/gc_implementation/concurrentMarkSweep/concurrentMarkSweepGeneration.cpp
index 5b88491..b24f8c3 100644
--- a/hotspot/src/share/vm/gc_implementation/concurrentMarkSweep/concurrentMarkSweepGeneration.cpp
+++ b/hotspot/src/share/vm/gc_implementation/concurrentMarkSweep/concurrentMarkSweepGeneration.cpp
@@ -1045,13 +1045,12 @@ CMSCollector::CMSCollector(ConcurrentMarkSweepGeneration* cmsGen,
              && _survivor_chunk_index == 0),
          "Error");
 
-  // Choose what strong roots should be scanned depending on verification options
-  // and perm gen collection mode.
+  // Choose what strong roots should be scanned.
+  // If CMSClassUnloadingEnabled is on, roots are set during
+  // setup_cms_unloading_and_verification_state() on each CMS cycle.
   if (!CMSClassUnloadingEnabled) {
     // If class unloading is disabled we want to include all classes into the root set.
     add_root_scanning_option(SharedHeap::SO_AllClasses);
-  } else {
-    add_root_scanning_option(SharedHeap::SO_SystemClasses);
   }
 
   NOT_PRODUCT(_overflow_counter = CMSMarkStackOverflowInterval;)
@@ -4393,6 +4392,19 @@ void CMSCollector::setup_cms_unloading_and_verification_state() {
                              || VerifyBeforeExit;
   const  int  rso           =   SharedHeap::SO_Strings | SharedHeap::SO_CodeCache;
 
+  // We set the proper root for this CMS cycle here.
+  // When class unloading is disabled, we set the default root scanning option
+  // once in the CMSCollector constructor.
+  if (CMSClassUnloadingEnabled) {
+    if (should_unload_classes()) {
+      remove_root_scanning_option(SharedHeap::SO_AllClasses);
+      add_root_scanning_option(SharedHeap::SO_SystemClasses);
+    } else {
+      remove_root_scanning_option(SharedHeap::SO_SystemClasses);
+      add_root_scanning_option(SharedHeap::SO_AllClasses);
+    }
+  }
+
   if (should_unload_classes()) {   // Should unload classes this cycle
     remove_root_scanning_option(rso);  // Shrink the root set appropriately
     set_verifying(should_verify);    // Set verification state for this cycle