diff -r 7504e7937183 -r 31b0e90ddbf0 src/hotspot/share/gc/z/zHeap.cpp
--- a/src/hotspot/share/gc/z/zHeap.cpp	Thu Aug 09 11:24:30 2018 +0200
+++ b/src/hotspot/share/gc/z/zHeap.cpp	Thu Aug 09 11:24:30 2018 +0200
@@ -96,7 +96,7 @@
 }
 
 bool ZHeap::is_initialized() const {
-  return _page_allocator.is_initialized();
+  return _page_allocator.is_initialized() && _mark.is_initialized();
 }
 
 size_t ZHeap::min_capacity() const {