diff --git a/widget/windows/nsWindow.cpp b/widget/windows/nsWindow.cpp
index 7ddf6077636b..32244d654969 100644
--- a/widget/windows/nsWindow.cpp
+++ b/widget/windows/nsWindow.cpp
@@ -594,7 +594,6 @@ class InitializeVirtualDesktopManagerTask : public Task {
 #endif
 
   virtual bool Run() override {
-#ifndef __MINGW32__
     if (!IsWin10OrLater()) {
       return true;
     }
@@ -608,7 +607,6 @@ class InitializeVirtualDesktopManagerTask : public Task {
     }
 
     gVirtualDesktopManager = desktopManager;
-#endif
     return true;
   }
 };
diff --git a/widget/windows/nsWindow.h b/widget/windows/nsWindow.h
index 6b134d87d575..3f6099ef6eda 100644
--- a/widget/windows/nsWindow.h
+++ b/widget/windows/nsWindow.h
@@ -97,6 +97,11 @@ IVirtualDesktopManager : public IUnknown {
       __RPC__in HWND topLevelWindow, __RPC__in REFGUID desktopId) = 0;
 };
 
+#ifdef __MINGW32__
+__CRT_UUID_DECL(IVirtualDesktopManager, 0xa5cd92ff, 0x29be, 0x454c, 0x8d, 0x04,
+                0xd8, 0x28, 0x79, 0xfb, 0x3f, 0x1b)
+#endif
+
 /**
  * Native WIN32 window wrapper.
  */