diff --git a/include/transport/config.h b/include/transport/config.h
index b79cb44b7885ad1a59cde95bdca8b236a6c8ec91..fe4ddfa40c07ebb65a9a93f7c2140bb95a4ae7d3 100644
--- a/include/transport/config.h
+++ b/include/transport/config.h
@@ -36,6 +36,7 @@
 
 namespace Transport {
 
+/// Represents variable:value pairs.
 typedef boost::program_options::variables_map Variables;
 
 /// Represents config file.