-XBT_PUBLIC xbt_dict_t sg_storage_get_properties(sg_storage_t storage);
-XBT_PUBLIC void sg_storage_set_property_value(sg_storage_t storage, const char* name, char* value);
-XBT_PUBLIC const char* sg_storage_get_property_value(sg_storage_t storage, const char* name);
+XBT_PUBLIC xbt_dict_t sg_storage_get_properties(const_sg_storage_t storage);
+XBT_PUBLIC void sg_storage_set_property_value(sg_storage_t storage, const char* name, const char* value);
+XBT_PUBLIC const char* sg_storage_get_property_value(const_sg_storage_t storage, const char* name);