diff --git a/src/square/ConsoleUI.cpp b/src/square/ConsoleUI.cpp
index 61e737f24..793ca89e3 100644
--- a/src/square/ConsoleUI.cpp
+++ b/src/square/ConsoleUI.cpp
@@ -69,6 +69,8 @@ ConsoleUI::~ConsoleUI()
 
 void ConsoleUI::Print(std::tstring s)
 {
+    boost::mutex::scoped_lock   lock(mutex);
+
 	tcout << "\n*******************************\n\n";
     std::tcout << s;
     tcout << "\n*******************************\n" << endl;
@@ -89,6 +91,8 @@ void ConsoleUI::Run()
 
 void ConsoleUI::PrintCommands()
 {
+    boost::mutex::scoped_lock   lock(mutex);
+
     tcout << "Commands:\n";
     tcout << "\tp [file]: play file (enter full path)\n";
     tcout << "\ts [n]: stop playing n-th file\n";
diff --git a/src/square/ConsoleUI.h b/src/square/ConsoleUI.h
index 5d4d79d0c..52e3cf9f3 100644
--- a/src/square/ConsoleUI.h
+++ b/src/square/ConsoleUI.h
@@ -39,6 +39,8 @@
 
 #include <vector>
 
+#include <boost/thread/mutex.hpp>
+
 #include "Transport.h"
 #include "DummyAudioEventHandler.h"
 
@@ -75,6 +77,8 @@ private: bool                       shouldQuit;
 private: Transport                  transport;
 private: DummyAudioEventHandler     audioEventHandler;
 
+private: boost::mutex   mutex;
+
 private: void ShutDown();
 public: static DWORD WINAPI ThreadRun(LPVOID param);
 };