diff -r e92153ed8bdc -r 29b0d0b61615 src/hotspot/share/gc/z/zArray.inline.hpp
--- a/src/hotspot/share/gc/z/zArray.inline.hpp	Mon Nov 25 12:30:24 2019 +0100
+++ b/src/hotspot/share/gc/z/zArray.inline.hpp	Mon Nov 25 12:31:39 2019 +0100
@@ -101,7 +101,7 @@
 template <typename T, bool parallel>
 inline bool ZArrayIteratorImpl<T, parallel>::next(T* elem) {
   if (parallel) {
-    const size_t next = Atomic::add(1u, &_next) - 1u;
+    const size_t next = Atomic::add(&_next, 1u) - 1u;
     if (next < _array->size()) {
       *elem = _array->at(next);
       return true;