Index: runtime/src/kmp_lock.cpp
===================================================================
--- runtime/src/kmp_lock.cpp
+++ runtime/src/kmp_lock.cpp
@@ -1456,6 +1456,7 @@
       }
       dequeued = FALSE;
     } else {
+      KMP_MB();
       tail = *tail_id_p;
       if (head == tail) { /* only one thread on the queue */
 #ifdef DEBUG_QUEUING_LOCKS
Index: runtime/test/worksharing/single/omp_single_copyprivate.c
===================================================================
--- runtime/test/worksharing/single/omp_single_copyprivate.c
+++ runtime/test/worksharing/single/omp_single_copyprivate.c
@@ -13,7 +13,7 @@
 
   result = 0;
   nr_iterations = 0;
-  #pragma omp parallel
+  #pragma omp parallel num_threads(4)
   {
     int i;
     for (i = 0; i < LOOPCOUNT; i++)