diff --git a/src/option.h b/src/option.h
index e2a4a839..eacc65d1 100644
--- a/src/option.h
+++ b/src/option.h
@@ -209,6 +209,8 @@ public:
 
 #define CTOR(type, name)                                \
   name ## option_t() : option_t<type>(#name)
+#define CTOR_(type, name, base)                         \
+  name ## option_t() : option_t<type>(#name), base
 #define DECL1(type, name, vartype, var, value)          \
   vartype var ;                                         \
   name ## option_t() : option_t<type>(#name), var(value)