diff --git a/include/yaml-cpp/contrib/graphbuilder.h b/include/yaml-cpp/contrib/graphbuilder.h
index 2ea139b..f2237e3 100644
--- a/include/yaml-cpp/contrib/graphbuilder.h
+++ b/include/yaml-cpp/contrib/graphbuilder.h
@@ -5,11 +5,11 @@
 #pragma once
 #endif
 
+#include "yaml-cpp/mark.h"
 #include <string>
 
 namespace YAML
 {
-  struct Mark;
   class Parser;
   
   // GraphBuilderInterface