diff --git a/GUI/host/textthread.cc b/GUI/host/textthread.cc
index e9856d6..f7bad29 100644
--- a/GUI/host/textthread.cc
+++ b/GUI/host/textthread.cc
@@ -9,6 +9,7 @@ TextThread::TextThread(ThreadParam tp, DWORD status) : tp(tp), status(status) {}
 
 TextThread::~TextThread()
 {
+	LOCK(ttMutex);
 	SetEvent(deletionEvent);
 	flushThread.join();
 	CloseHandle(deletionEvent);