diff --git a/FlashMQTests/tst_maintests.cpp b/FlashMQTests/tst_maintests.cpp
index 4d44f98..ce53660 100644
--- a/FlashMQTests/tst_maintests.cpp
+++ b/FlashMQTests/tst_maintests.cpp
@@ -1002,6 +1002,7 @@ void MainTests::testSavingSessions()
         // Kind of a hack...
         Authentication auth(*settings.get());
         ThreadGlobals::assign(&auth);
+        ThreadGlobals::assignThreadData(t.get());
 
         std::shared_ptr<Client> c1(new Client(0, t, nullptr, false, nullptr, settings.get(), false));
         c1->setClientProperties(ProtocolVersion::Mqtt311, "c1", "user1", true, 60);
diff --git a/client.cpp b/client.cpp
index 069e83e..95b1c2b 100644
--- a/client.cpp
+++ b/client.cpp
@@ -45,6 +45,7 @@ Client::Client(int fd, std::shared_ptr<ThreadData> threadData, SSL *ssl, bool we
     ioWrapper(ssl, websocket, initialBufferSize, this),
     readbuf(initialBufferSize),
     writebuf(initialBufferSize),
+    epoll_fd(threadData ? threadData->epollfd : 0),
     threadData(threadData)
 {
     int flags = fcntl(fd, F_GETFL);
@@ -61,7 +62,7 @@ Client::Client(int fd, std::shared_ptr<ThreadData> threadData, SSL *ssl, bool we
 Client::~Client()
 {
     // Dummy clients, that I sometimes need just because the interface demands it but there's not actually a client, have no thread.
-    if (!this->threadData)
+    if (this->threadData.expired())
         return;
 
     if (disconnectReason.empty())
@@ -78,7 +79,7 @@ Client::~Client()
 
     if (fd > 0) // this check is essentially for testing, when working with a dummy fd.
     {
-        if (epoll_ctl(threadData->epollfd, EPOLL_CTL_DEL, fd, NULL) != 0)
+        if (epoll_ctl(this->epoll_fd, EPOLL_CTL_DEL, fd, NULL) != 0)
             logger->logf(LOG_ERR, "Removing fd %d of client '%s' from epoll produced error: %s", fd, repr().c_str(), strerror(errno));
         close(fd);
     }
@@ -272,7 +273,9 @@ void Client::writeMqttPacketAndBlameThisClient(const MqttPacket &packet)
     }
     catch (std::exception &ex)
     {
-        threadData->removeClientQueued(fd);
+        std::shared_ptr<ThreadData> td = this->threadData.lock();
+        if (td)
+            td->removeClientQueued(fd);
     }
 }
 
@@ -414,7 +417,7 @@ uint16_t Client::getMaxIncomingTopicAliasValue() const
 
 void Client::sendOrQueueWill()
 {
-    if (!this->threadData)
+    if (this->threadData.expired())
         return;
 
     if (!this->willPublish)
@@ -447,7 +450,10 @@ void Client::serverInitiatedDisconnect(ReasonCodes reason)
     else
     {
         markAsDisconnecting();
-        threadData->removeClientQueued(fd);
+
+        std::shared_ptr<ThreadData> td = this->threadData.lock();
+        if (td)
+            td->removeClientQueued(fd);
     }
 }
 
@@ -573,7 +579,7 @@ void Client::setReadyForWriting(bool val)
     memset(&ev, 0, sizeof (struct epoll_event));
     ev.data.fd = fd;
     ev.events = readyForReading*EPOLLIN | readyForWriting*EPOLLOUT;
-    check<std::runtime_error>(epoll_ctl(threadData->epollfd, EPOLL_CTL_MOD, fd, &ev));
+    check<std::runtime_error>(epoll_ctl(this->epoll_fd, EPOLL_CTL_MOD, fd, &ev));
 }
 
 void Client::setReadyForReading(bool val)
@@ -606,7 +612,7 @@ void Client::setReadyForReading(bool val)
         std::lock_guard<std::mutex> locker(writeBufMutex);
 
         ev.events = readyForReading*EPOLLIN | readyForWriting*EPOLLOUT;
-        check<std::runtime_error>(epoll_ctl(threadData->epollfd, EPOLL_CTL_MOD, fd, &ev));
+        check<std::runtime_error>(epoll_ctl(this->epoll_fd, EPOLL_CTL_MOD, fd, &ev));
     }
 }
 
diff --git a/client.h b/client.h
index dd66abb..7de28ed 100644
--- a/client.h
+++ b/client.h
@@ -93,7 +93,8 @@ class Client
 
     std::shared_ptr<WillPublish> willPublish;
 
-    std::shared_ptr<ThreadData> threadData;
+    const int epoll_fd;
+    std::weak_ptr<ThreadData> threadData; // The thread (data) that this client 'lives' in.
     std::mutex writeBufMutex;
 
     std::shared_ptr<Session> session;
@@ -139,7 +140,6 @@ public:
     void setAuthenticated(bool value) { authenticated = value;}
     bool getAuthenticated() { return authenticated; }
     bool hasConnectPacketSeen() { return connectPacketSeen; }
-    std::shared_ptr<ThreadData> getThreadData() { return threadData; }
     std::string &getClientId() { return this->clientid; }
     const std::string &getUsername() const { return this->username; }
     std::string &getMutableUsername();
diff --git a/mqttpacket.cpp b/mqttpacket.cpp
index 984f814..8662f4a 100644
--- a/mqttpacket.cpp
+++ b/mqttpacket.cpp
@@ -328,7 +328,7 @@ void MqttPacket::handleConnect()
 
     std::shared_ptr<SubscriptionStore> subscriptionStore = MainApp::getMainApp()->getSubscriptionStore();
 
-    sender->getThreadData()->mqttConnectCounter.inc();
+    ThreadGlobals::getThreadData()->mqttConnectCounter.inc();
 
     uint16_t variable_header_length = readTwoBytesToUInt16();
 
@@ -864,7 +864,7 @@ void MqttPacket::handleDisconnect()
     sender->markAsDisconnecting();
     if (reasonCode == ReasonCodes::Success)
         sender->clearWill();
-    sender->getThreadData()->removeClientQueued(sender);
+    ThreadGlobals::getThreadData()->removeClientQueued(sender);
 }
 
 void MqttPacket::handleSubscribe()
@@ -1131,7 +1131,7 @@ void MqttPacket::handlePublish()
 
     ReasonCodes ackCode = ReasonCodes::Success;
 
-    sender->getThreadData()->receivedMessageCounter.inc();
+    ThreadGlobals::getThreadData()->receivedMessageCounter.inc();
 
     Authentication &authentication = *ThreadGlobals::getAuth();
 
diff --git a/subscriptionstore.cpp b/subscriptionstore.cpp
index a7ca0f1..c76107c 100644
--- a/subscriptionstore.cpp
+++ b/subscriptionstore.cpp
@@ -225,7 +225,7 @@ void SubscriptionStore::registerClientAndKickExistingOne(std::shared_ptr<Client>
 // Removes an existing client when it already exists [MQTT-3.1.4-2].
 void SubscriptionStore::registerClientAndKickExistingOne(std::shared_ptr<Client> &client, bool clean_start, uint16_t clientReceiveMax, uint32_t sessionExpiryInterval)
 {
-    client->getThreadData()->queueClientNextKeepAliveCheckLocked(client, true);
+    ThreadGlobals::getThreadData()->queueClientNextKeepAliveCheckLocked(client, true);
 
     RWLockGuard lock_guard(&subscriptionsRwlock);
     lock_guard.wrlock();