diff --git a/launcher/Application.cpp b/launcher/Application.cpp
index 9a1ed440e5..11b80a0063 100644
--- a/launcher/Application.cpp
+++ b/launcher/Application.cpp
@@ -48,6 +48,7 @@
 #include "net/PasteUpload.h"
 #include "pathmatcher/MultiMatcher.h"
 #include "pathmatcher/SimplePrefixMatcher.h"
+#include "tasks/Task.h"
 #include "tools/GenericProfiler.h"
 #include "ui/InstanceWindow.h"
 #include "ui/MainWindow.h"
@@ -1397,6 +1398,7 @@ bool Application::launch(InstancePtr instance,
     if (m_updateRunning) {
         qDebug() << "Cannot launch instances while an update is running. Please try again when updates are completed.";
     } else if (instance->canLaunch()) {
+        QMutexLocker locker(&m_instanceExtrasMutex);
         auto& extras = m_instanceExtras[instance->id()];
         auto window = extras.window;
         if (window) {
@@ -1422,7 +1424,7 @@ bool Application::launch(InstancePtr instance,
         connect(controller.get(), &LaunchController::failed, this, &Application::controllerFailed);
         connect(controller.get(), &LaunchController::aborted, this, [this] { controllerFailed(tr("Aborted")); });
         addRunningInstance();
-        controller->start();
+        QMetaObject::invokeMethod(controller.get(), &Task::start, Qt::QueuedConnection);
         return true;
     } else if (instance->isRunning()) {
         showInstanceWindow(instance, "console");
@@ -1440,9 +1442,11 @@ bool Application::kill(InstancePtr instance)
         qWarning() << "Attempted to kill instance" << instance->id() << ", which isn't running.";
         return false;
     }
+    QMutexLocker locker(&m_instanceExtrasMutex);
     auto& extras = m_instanceExtras[instance->id()];
     // NOTE: copy of the shared pointer keeps it alive
     auto controller = extras.controller;
+    locker.unlock();
     if (controller) {
         return controller->abort();
     }
@@ -1496,6 +1500,8 @@ void Application::controllerSucceeded()
     if (!controller)
         return;
     auto id = controller->id();
+
+    QMutexLocker locker(&m_instanceExtrasMutex);
     auto& extras = m_instanceExtras[id];
 
     // on success, do...
@@ -1521,6 +1527,7 @@ void Application::controllerFailed(const QString& error)
     if (!controller)
         return;
     auto id = controller->id();
+    QMutexLocker locker(&m_instanceExtrasMutex);
     auto& extras = m_instanceExtras[id];
 
     // on failure, do... nothing
@@ -1578,6 +1585,7 @@ InstanceWindow* Application::showInstanceWindow(InstancePtr instance, QString pa
     if (!instance)
         return nullptr;
     auto id = instance->id();
+    QMutexLocker locker(&m_instanceExtrasMutex);
     auto& extras = m_instanceExtras[id];
     auto& window = extras.window;
 
@@ -1615,6 +1623,7 @@ void Application::on_windowClose()
     m_openWindows--;
     auto instWindow = qobject_cast<InstanceWindow*>(QObject::sender());
     if (instWindow) {
+        QMutexLocker locker(&m_instanceExtrasMutex);
         auto& extras = m_instanceExtras[instWindow->instanceId()];
         extras.window = nullptr;
         if (extras.controller) {
diff --git a/launcher/Application.h b/launcher/Application.h
index 6b218f9f89..dad76d7026 100644
--- a/launcher/Application.h
+++ b/launcher/Application.h
@@ -280,6 +280,7 @@ class Application : public QApplication {
         shared_qobject_ptr<LaunchController> controller;
     };
     std::map<QString, InstanceXtras> m_instanceExtras;
+    mutable QMutex m_instanceExtrasMutex;
 
     // main state variables
     size_t m_openWindows = 0;