--- a/widget/windows/WinUtils.h
+++ b/widget/windows/WinUtils.h
@@ -73,17 +73,17 @@ protected:                              
   nsAutoRefCnt mRefCnt;                                                       \
   NS_DECL_OWNINGTHREAD                                                        \
 public:
 
 class nsWindow;
 class nsWindowBase;
 struct KeyPair;
 
-#ifndef DPI_AWARENESS_CONTEXT_DECLARED
+#if !defined(DPI_AWARENESS_CONTEXT_DECLARED) && !defined(DPI_AWARENESS_CONTEXT_UNAWARE)
 
 DECLARE_HANDLE(DPI_AWARENESS_CONTEXT);
 
 typedef enum DPI_AWARENESS {
   DPI_AWARENESS_INVALID = -1,
   DPI_AWARENESS_UNAWARE = 0,
   DPI_AWARENESS_SYSTEM_AWARE = 1,
   DPI_AWARENESS_PER_MONITOR_AWARE = 2