--- a/src/hotspot/share/gc/shenandoah/shenandoahTaskqueue.hpp	Mon Nov 25 12:30:24 2019 +0100
+++ b/src/hotspot/share/gc/shenandoah/shenandoahTaskqueue.hpp	Mon Nov 25 12:31:39 2019 +0100
@@ -304,7 +304,7 @@
     return NULL;
   }
 
-  jint index = Atomic::add(1, &_claimed_index);
+  jint index = Atomic::add(&_claimed_index, 1);
 
   if (index <= size) {
     return GenericTaskQueueSet<T, F>::queue((uint)index - 1);