diff --git a/ISLE/isle.h b/ISLE/isle.h
index e23fb8cb..389e8630 100644
--- a/ISLE/isle.h
+++ b/ISLE/isle.h
@@ -1,7 +1,7 @@
 #ifndef ISLE_H
 #define ISLE_H
 
-#include <Windows.h>
+#include <windows.h>
 
 #include "mxresult.h"
 #include "mxvideoparam.h"
diff --git a/ISLE/main.cpp b/ISLE/main.cpp
index 89284948..04dfe912 100644
--- a/ISLE/main.cpp
+++ b/ISLE/main.cpp
@@ -1,5 +1,5 @@
-#include <DSOUND.H>
-#include <Windows.h>
+#include <dsound.h>
+#include <windows.h>
 
 #include "define.h"
 #include "isle.h"
diff --git a/LEGO1/dllmain.cpp b/LEGO1/dllmain.cpp
index 060bd70c..673b5e4f 100644
--- a/LEGO1/dllmain.cpp
+++ b/LEGO1/dllmain.cpp
@@ -1,4 +1,4 @@
-#include <Windows.h>
+#include <windows.h>
 
 BOOL WINAPI DllMain(HINSTANCE hinstDLL, DWORD fdwReason, LPVOID lpvReserved)
 {
diff --git a/LEGO1/mxcriticalsection.h b/LEGO1/mxcriticalsection.h
index bd84babb..81d96d37 100644
--- a/LEGO1/mxcriticalsection.h
+++ b/LEGO1/mxcriticalsection.h
@@ -1,7 +1,7 @@
 #ifndef MXCRITICALSECTION_H
 #define MXCRITICALSECTION_H
 
-#include <Windows.h>
+#include <windows.h>
 
 class MxCriticalSection
 {
diff --git a/LEGO1/mxomnicreateparam.h b/LEGO1/mxomnicreateparam.h
index c1e8570f..987efb72 100644
--- a/LEGO1/mxomnicreateparam.h
+++ b/LEGO1/mxomnicreateparam.h
@@ -1,7 +1,7 @@
 #ifndef MXOMNICREATEPARAM_H
 #define MXOMNICREATEPARAM_H
 
-#include <Windows.h>
+#include <windows.h>
 
 #include "mxomnicreateflags.h"
 #include "mxomnicreateparambase.h"