diff --git a/aos/configuration.cc b/aos/configuration.cc
index ad2e295..6fce2e0 100644
--- a/aos/configuration.cc
+++ b/aos/configuration.cc
@@ -631,7 +631,8 @@
             << type << "\" }";
   }
 
-  // Then look for the channel.
+  // Then look for the channel (note that this relies on the channels being
+  // sorted in the config).
   auto channel_iterator =
       std::lower_bound(config->channels()->cbegin(), config->channels()->cend(),
                        std::make_pair(name, type), CompareChannels);