--- a/src/hotspot/share/gc/shenandoah/shenandoahJfrSupport.cpp	Wed May 22 09:33:22 2019 +0200
+++ b/src/hotspot/share/gc/shenandoah/shenandoahJfrSupport.cpp	Wed May 22 08:42:00 2019 +0100
@@ -57,7 +57,7 @@
 public:
   virtual void heap_region_do(ShenandoahHeapRegion* r) {
     EventShenandoahHeapRegionInformation evt;
-    evt.set_index(r->region_number());
+    evt.set_index((unsigned)r->region_number());
     evt.set_state((u8)r->state());
     evt.set_start((uintptr_t)r->bottom());
     evt.set_used(r->used());