diff --git a/src/TopicTree.h b/src/TopicTree.h
index 22fba82..c1ee999 100644
--- a/src/TopicTree.h
+++ b/src/TopicTree.h
@@ -1,5 +1,5 @@
 /*
- * Authored by Alex Hultman, 2018-2019.
+ * Authored by Alex Hultman, 2018-2020.
  * Intellectual property of third-party.
 
  * Licensed under the Apache License, Version 2.0 (the "License");
@@ -26,6 +26,7 @@
 #include <set>
 #include <chrono>
 #include <list>
+#include <cstring>
 
 namespace uWS {
 
diff --git a/tests/Makefile b/tests/Makefile
index 100e8cf..7c9acff 100644
--- a/tests/Makefile
+++ b/tests/Makefile
@@ -1,3 +1,5 @@
 default:
-	$(CXX) -std=c++17 HttpRouter.cpp -o HttpRouter
+	$(CXX) -std=c++17 -fsanitize=address TopicTree.cpp -o TopicTree
+	./TopicTree
+	$(CXX) -std=c++17 -fsanitize=address HttpRouter.cpp -o HttpRouter
 	./HttpRouter
\ No newline at end of file
diff --git a/tests/TopicTree.cpp b/tests/TopicTree.cpp
new file mode 100644
index 0000000..de9b84e
--- /dev/null
+++ b/tests/TopicTree.cpp
@@ -0,0 +1,49 @@
+#include "../src/TopicTree.h"
+
+#include <cassert>
+#include <iostream>
+
+uWS::TopicTree *topicTree;
+
+void testUnsubscribeInside() {
+
+    topicTree = new uWS::TopicTree([](uWS::Subscriber *s, std::string_view data) {
+        std::cout << s << " got <" << data << ">" << std::endl;
+
+        if (s == (void *) UINTPTR_MAX) {
+            std::cout << "Error! Received UINTPTR_MAX as Subscriber!" << std::endl;
+            exit(-1);
+        }
+
+        /* This one causes the following cb to get UINTPTR_MAX */
+        topicTree->unsubscribeAll(s);
+
+        return 0;
+    });
+
+    uWS::Subscriber *s1 = new uWS::Subscriber(nullptr);
+    uWS::Subscriber *s2 = new uWS::Subscriber(nullptr);
+
+    std::cout << "s1 = " << s1 << std::endl;
+    std::cout << "s2 = " << s2 << std::endl;
+
+    topicTree->subscribe("1", s1);
+    topicTree->subscribe("2", s2);
+
+    topicTree->publish("1", "Ett!");
+    topicTree->publish("2", "Två!");
+
+    topicTree->drain();
+
+    topicTree->unsubscribeAll(s1);
+    topicTree->unsubscribeAll(s2);
+
+    delete s1;
+    delete s2;
+
+    delete topicTree;
+}
+
+int main() {
+    testUnsubscribeInside();
+}
\ No newline at end of file