--- old/src/hotspot/share/gc/g1/g1ConcurrentMark.hpp	2019-11-04 17:37:55.544968794 +0100
+++ new/src/hotspot/share/gc/g1/g1ConcurrentMark.hpp	2019-11-04 17:37:55.340967733 +0100
@@ -32,6 +32,7 @@
 #include "gc/g1/heapRegionSet.hpp"
 #include "gc/shared/taskqueue.hpp"
 #include "gc/shared/verifyOption.hpp"
+#include "gc/shared/workgroup.hpp"
 #include "memory/allocation.hpp"
 #include "utilities/compilerWarnings.hpp"