diff --git a/generator/intermediate_data.hpp b/generator/intermediate_data.hpp
index ff1c77acfb..ddea7f2da8 100644
--- a/generator/intermediate_data.hpp
+++ b/generator/intermediate_data.hpp
@@ -311,7 +311,7 @@ private:
   struct ElementProcessorBase
   {
   protected:
-    CacheReader m_reader;
+    CacheReader & m_reader;
     ToDo & m_toDo;
 
   public: