diff --git a/src/TopicTree.h b/src/TopicTree.h
index 6d11c4d..44cb4fb 100644
--- a/src/TopicTree.h
+++ b/src/TopicTree.h
@@ -76,7 +76,7 @@ struct Intersection {
     std::pair<std::string, std::string> dataChannels;
     std::vector<Hole> holes;
 
-    void forSubscriber(std::vector<unsigned int> &senderForMessages, std::function<void(std::pair<std::string_view, std::string_view>)> cb) {
+    void forSubscriber(std::vector<unsigned int> &senderForMessages, std::function<void(std::pair<std::string_view, std::string_view>, bool)> cb) {
         /* How far we already emitted of the two dataChannels */
         std::pair<size_t, size_t> emitted = {};
 
@@ -111,7 +111,8 @@ struct Intersection {
                     std::string_view(dataChannels.second.data() + emitted.second, toEmit.second),
                 };
 
-                cb(cutDataChannels);
+                /* We only need to test the first data channel for "FIN" */
+                cb(cutDataChannels, emitted.first + toEmit.first + toIgnore.first == dataChannels.first.length());
             }
 
             emitted.first += toEmit.first + toIgnore.first;
@@ -127,7 +128,7 @@ struct Intersection {
             std::string_view(dataChannels.second.data() + emitted.second, dataChannels.second.length() - emitted.second),
         };
 
-        cb(cutDataChannels);
+        cb(cutDataChannels, true);
     }
 };
 
diff --git a/tests/TopicTree.cpp b/tests/TopicTree.cpp
index 8d1ef9f..389d1aa 100644
--- a/tests/TopicTree.cpp
+++ b/tests/TopicTree.cpp
@@ -19,11 +19,25 @@ void testCorrectness() {
 
     topicTree = new uWS::TopicTree([&topicTree, &actualResult](uWS::Subscriber *s, uWS::Intersection &intersection) {
 
-        intersection.forSubscriber(topicTree->getSenderFor(s), [s, &actualResult](std::pair<std::string_view, std::string_view> dataChannels) {
+        /* How many bytes we have in first data channel at time we get fin = true */
+        unsigned int finAt = 0;
+
+        intersection.forSubscriber(topicTree->getSenderFor(s), [s, &finAt, &actualResult](std::pair<std::string_view, std::string_view> dataChannels, bool fin) {
             actualResult[s].first += dataChannels.first;
             actualResult[s].second += dataChannels.second;
+
+            /* Check that getting fin = true really is the last segment */
+            if (!finAt && fin) {
+                finAt = actualResult[s].first.length();
+            }
         });
 
+        /* Assume finAt == actualResult[s].first.length() */
+        if (actualResult[s].first.length() != finAt) {
+            std::cout << "ERROR! FinAt mismatching!" << std::endl;
+            exit(1);
+        }
+
         /* We actually don't use this one */
         return 0;
     });