diff --git a/src/ripple/rpc/Coroutine.h b/src/ripple/rpc/Coroutine.h
index 1a42ab533..81964f759 100644
--- a/src/ripple/rpc/Coroutine.h
+++ b/src/ripple/rpc/Coroutine.h
@@ -41,7 +41,7 @@ public:
     void run ();
 
 private:
-    class Impl;
+    struct Impl;
     std::shared_ptr <Impl> impl_;
 
     Coroutine (std::shared_ptr <Impl> const&);