diff --git a/examples/CommNoGui/CSerialPortDemoNoGui.cpp b/examples/CommNoGui/CSerialPortDemoNoGui.cpp
index 1df728a..c26d162 100644
--- a/examples/CommNoGui/CSerialPortDemoNoGui.cpp
+++ b/examples/CommNoGui/CSerialPortDemoNoGui.cpp
@@ -1,7 +1,7 @@
 #include <iostream>
 
 #ifdef _WIN32
-#include <Windows.h>
+#include <windows.h>
 #define imsleep(microsecond) Sleep(microsecond) // ms
 #else
 #include <unistd.h>
diff --git a/src/SerialPortInfoWinBase.cpp b/src/SerialPortInfoWinBase.cpp
index fbdc020..a0da5d6 100644
--- a/src/SerialPortInfoWinBase.cpp
+++ b/src/SerialPortInfoWinBase.cpp
@@ -1,6 +1,6 @@
-#include <Windows.h>
+#include <windows.h>
 #include <initguid.h> // GUID
-#include <Setupapi.h> // SetupDiGetClassDevs Setup*
+#include <setupapi.h> // SetupDiGetClassDevs Setup*
 #include <tchar.h>    // _T
 
 #include "CSerialPort/iutils.hpp"
diff --git a/test/CSerialPortVirtual.cpp b/test/CSerialPortVirtual.cpp
index 2e0e718..15a58ce 100644
--- a/test/CSerialPortVirtual.cpp
+++ b/test/CSerialPortVirtual.cpp
@@ -2,7 +2,7 @@
 #include "CSerialPort/iutils.hpp"
 
 #ifdef _WIN32
-#include <Windows.h>
+#include <windows.h>
 #include <tchar.h> //_T
 #else
 #include <errno.h>      // perror
diff --git a/test/cseiralport_test.cpp b/test/cseiralport_test.cpp
index 38e2ae0..6c9e7fb 100644
--- a/test/cseiralport_test.cpp
+++ b/test/cseiralport_test.cpp
@@ -2,7 +2,7 @@
 #include <vector>
 
 #ifdef _WIN32
-#include <Windows.h>
+#include <windows.h>
 #define imsleep(microsecond) Sleep(microsecond) // ms
 #else
 #include <unistd.h>