diff --git a/common/include/fwd-valptridx.h b/common/include/fwd-valptridx.h
index 3b89e0e4a..2542f1a73 100644
--- a/common/include/fwd-valptridx.h
+++ b/common/include/fwd-valptridx.h
@@ -9,6 +9,7 @@
 #include <functional>
 #include <cstddef>
 #include "dxxsconf.h"
+#include "cpp-valptridx.h"
 
 /* Unexpected invalid data can be handled in one of three ways.
  *