diff --git a/src/hotspot/share/utilities/rbTree.hpp b/src/hotspot/share/utilities/rbTree.hpp
index 36e60d853aa..89f9eb256bf 100644
--- a/src/hotspot/share/utilities/rbTree.hpp
+++ b/src/hotspot/share/utilities/rbTree.hpp
@@ -63,8 +63,8 @@ enum class RBTreeOrdering : int { LT, EQ, GT };
 
 template <typename K, typename NodeType, typename COMPARATOR>
 class AbstractRBTree;
-class outputStream;
 class Arena;
+class outputStream;
 class ResourceArea;
 
 class IntrusiveRBNode {