diff --git a/CellframeNodeDiagtool/WinDiagnostic.cpp b/CellframeNodeDiagtool/WinDiagnostic.cpp
index a1430322b69db00576155448376774beb5921fe6..6a514b3b83094d5890afbd03becd55a8ce273432 100644
--- a/CellframeNodeDiagtool/WinDiagnostic.cpp
+++ b/CellframeNodeDiagtool/WinDiagnostic.cpp
@@ -3,7 +3,7 @@
 #include <tlhelp32.h>
 #include "registry.h"
 #include <pdh.h>
-#include <windows.h>
+#include <Windows.h>
 #include <tlhelp32.h>
 
 WinDiagnostic::WinDiagnostic(AbstractDiagnostic *parent)