diff --git a/windows/runner/win32_window.cpp b/windows/runner/win32_window.cpp
index c10f08d..bd11548 100644
--- a/windows/runner/win32_window.cpp
+++ b/windows/runner/win32_window.cpp
@@ -105,6 +105,31 @@ Win32Window::~Win32Window() {
 bool Win32Window::CreateAndShow(const std::wstring& title,
                                 const Point& origin,
                                 const Size& size) {
+
+  HANDLE hMutexHandle=CreateMutex(NULL, TRUE, L"com.linloir.lchatclient.mutex");
+  HWND handle=FindWindowA(NULL, "tcp_client");
+
+  if (hMutexHandle == NULL || GetLastError() == ERROR_ALREADY_EXISTS)
+  {
+    WINDOWPLACEMENT place = {sizeof(WINDOWPLACEMENT)};
+    GetWindowPlacement(handle, &place);
+    switch (place.showCmd)
+    {
+      case SW_SHOWMAXIMIZED:
+        ShowWindow(handle, SW_SHOWMAXIMIZED);
+        break;
+      case SW_SHOWMINIMIZED:
+        ShowWindow(handle, SW_RESTORE);
+        break;
+      default:
+        ShowWindow(handle, SW_NORMAL);
+        break;
+    }
+    SetWindowPos(0, HWND_TOP, 0, 0, 0, 0, SWP_SHOWWINDOW | SWP_NOSIZE | SWP_NOMOVE);
+    SetForegroundWindow(handle);
+    return 0;
+  }
+
   Destroy();
 
   const wchar_t* window_class =