diff --git a/contrib/epee/include/serialization/keyvalue_serialization.h b/contrib/epee/include/serialization/keyvalue_serialization.h
index bf2c8dac..f4442e46 100644
--- a/contrib/epee/include/serialization/keyvalue_serialization.h
+++ b/contrib/epee/include/serialization/keyvalue_serialization.h
@@ -70,6 +70,12 @@ public: \
 #define KV_SERIALIZE_N(varialble, val_name) \
   epee::serialization::selector<is_store>::serialize(this_ref.varialble, stg, hparent_section, val_name);
 
+#define KV_SERIALIZE_OPT_N(variable, val_name, default_value) \
+  do { \
+    if (!epee::serialization::selector<is_store>::serialize(this_ref.variable, stg, hparent_section, val_name)) \
+      this_ref.variable = default_value; \
+  } while (0);
+
 #define KV_SERIALIZE_VAL_POD_AS_BLOB_FORCE_N(varialble, val_name) \
   epee::serialization::selector<is_store>::serialize_t_val_as_blob(this_ref.varialble, stg, hparent_section, val_name); 
 
@@ -86,6 +92,7 @@ public: \
 #define KV_SERIALIZE_VAL_POD_AS_BLOB(varialble)           KV_SERIALIZE_VAL_POD_AS_BLOB_N(varialble, #varialble)
 #define KV_SERIALIZE_VAL_POD_AS_BLOB_FORCE(varialble)     KV_SERIALIZE_VAL_POD_AS_BLOB_FORCE_N(varialble, #varialble) //skip is_pod compile time check
 #define KV_SERIALIZE_CONTAINER_POD_AS_BLOB(varialble)     KV_SERIALIZE_CONTAINER_POD_AS_BLOB_N(varialble, #varialble)
+#define KV_SERIALIZE_OPT(variable,default_value)          KV_SERIALIZE_OPT_N(variable, #variable, default_value)
 
 }