diff --git a/src/share/vm/gc_implementation/g1/concurrentMarkThread.cpp b/src/share/vm/gc_implementation/g1/concurrentMarkThread.cpp
index 8186e61ce043cccbe63b3ec0ab67dfded0ca7e4c..91fdd4a1996dfb07df251fac355e7e2d63590921 100644
--- a/src/share/vm/gc_implementation/g1/concurrentMarkThread.cpp
+++ b/src/share/vm/gc_implementation/g1/concurrentMarkThread.cpp
@@ -251,7 +251,9 @@ void ConcurrentMarkThread::run() {
 
         // Now do the remainder of the cleanup operation.
         _cm->completeCleanup();
+        _sts.join();
         g1_policy->record_concurrent_mark_cleanup_completed();
+        _sts.leave();
 
         double cleanup_end_sec = os::elapsedTime();
         if (PrintGC) {
diff --git a/src/share/vm/gc_implementation/g1/heapRegionSeq.cpp b/src/share/vm/gc_implementation/g1/heapRegionSeq.cpp
index 0363352af723d6c47ad229cfc0f6a5af24584fe2..2e15190c526570d4d7e3794d6933c625cdedc6a0 100644
--- a/src/share/vm/gc_implementation/g1/heapRegionSeq.cpp
+++ b/src/share/vm/gc_implementation/g1/heapRegionSeq.cpp
@@ -195,10 +195,10 @@ int HeapRegionSeq::find_contiguous(size_t num) {
     assert(0 <= res && res < _regions.length(),
            err_msg("res: %d should be valid", res));
     _alloc_search_start = res + (int) num;
+    assert(0 < _alloc_search_start && _alloc_search_start <= _regions.length(),
+           err_msg("_alloc_search_start: %d should be valid",
+                   _alloc_search_start));
   }
-  assert(0 < _alloc_search_start && _alloc_search_start <= _regions.length(),
-         err_msg("_alloc_search_start: %d should be valid",
-                 _alloc_search_start));
   return res;
 }