diff --git a/main.cpp b/main.cpp
index 0fcebc0..49da151 100644
--- a/main.cpp
+++ b/main.cpp
@@ -631,7 +631,8 @@ void addChannelToTreat(unsigned short threadId, string channelId)
     channelsAlreadyTreatedAndToTreatMutex.lock();
     if(channelsAlreadyTreated.find(channelId) == channelsAlreadyTreated.end() && channelsToTreatRev.find(channelId) == channelsToTreatRev.end())
     {
-        unsigned int channelsToTreatIndex = channelsToTreat.end()->first + 1;
+        // It is unclear to me why `channelsToTreat.end()->first + 1` doesn't work here.
+        unsigned int channelsToTreatIndex = channelsToTreat.rbegin()->first + 1;
         channelsToTreat[channelsToTreatIndex] = channelId;
         channelsToTreatRev[channelId] = channelsToTreatIndex;