diff --git a/src/hotspot/share/gc/g1/g1HeapTransition.cpp b/src/hotspot/share/gc/g1/g1HeapTransition.cpp
index a2097041b20..4f759b4a606 100644
--- a/src/hotspot/share/gc/g1/g1HeapTransition.cpp
+++ b/src/hotspot/share/gc/g1/g1HeapTransition.cpp
@@ -62,7 +62,7 @@ G1HeapTransition::Data::~Data() {
 
 G1HeapTransition::G1HeapTransition(G1CollectedHeap* g1_heap) : _g1_heap(g1_heap), _before(g1_heap) { }
 
-struct DetailedUsage : public StackObj {
+struct G1HeapTransition::DetailedUsage : public StackObj {
   size_t _eden_used;
   size_t _survivor_used;
   size_t _old_used;
@@ -79,7 +79,7 @@ struct DetailedUsage : public StackObj {
     _humongous_region_count(0) {}
 };
 
-class DetailedUsageClosure: public HeapRegionClosure {
+class G1HeapTransition::DetailedUsageClosure: public HeapRegionClosure {
 public:
   DetailedUsage _usage;
   bool do_heap_region(HeapRegion* r) {
diff --git a/src/hotspot/share/gc/g1/g1HeapTransition.hpp b/src/hotspot/share/gc/g1/g1HeapTransition.hpp
index 09d901f283c..54f87fd3b71 100644
--- a/src/hotspot/share/gc/g1/g1HeapTransition.hpp
+++ b/src/hotspot/share/gc/g1/g1HeapTransition.hpp
@@ -31,6 +31,9 @@
 class G1CollectedHeap;
 
 class G1HeapTransition {
+  struct DetailedUsage;
+  class DetailedUsageClosure;
+
   struct Data {
     size_t _eden_length;
     size_t _survivor_length;