diff --git a/src/raspberrypi/os.cpp b/src/raspberrypi/os.cpp
index ac6b3f5..49c1998 100644
--- a/src/raspberrypi/os.cpp
+++ b/src/raspberrypi/os.cpp
@@ -1,3 +1,15 @@
+//---------------------------------------------------------------------------
+//
+//	SCSI Target Emulator RaSCSI (*^..^*)
+//	for Raspberry Pi
+//
+//	Powered by XM6 TypeG Technology.
+//	Copyright (C) 2016-2020 GIMONS
+//  Copyright (C) 2020 akuker
+//
+//	[ OS specific features / glue logic ]
+//
+//---------------------------------------------------------------------------
 #include "os.h"
 
 //---------------------------------------------------------------------------
@@ -23,6 +35,10 @@ void FixCpu(int cpu)
 		sched_setaffinity(0, sizeof(cpu_set_t), &cpuset);
 	}
 #else
+	// RaSCSI itself only functions on a Raspberry Pi. However, the
+	// unit tests should run on other hosts. For example, the github
+	// action runners are only Ubuntu x86_64. Some developers may also
+	// want to be able to run the unit tests on MacOS.
     return;
 #endif
 }
diff --git a/src/raspberrypi/os.h b/src/raspberrypi/os.h
index f249cbc..d298269 100644
--- a/src/raspberrypi/os.h
+++ b/src/raspberrypi/os.h
@@ -8,12 +8,11 @@
 //
 //	Imported NetBSD support and some optimisation patch by Rin Okuyama.
 //
-//	[ OS固有 ]
+//	[ OS specific features / glue logic ]
 //
 //---------------------------------------------------------------------------
 
-#if !defined(os_h)
-#define os_h
+#pragma once
 
 //---------------------------------------------------------------------------
 //
@@ -88,7 +87,7 @@
 
 //---------------------------------------------------------------------------
 //
-//	基本マクロ
+//	Base Macros
 //
 //---------------------------------------------------------------------------
 #undef FASTCALL
@@ -120,7 +119,7 @@
 
 //---------------------------------------------------------------------------
 //
-//	基本型定義
+//	Basic Type Definitions
 //
 //---------------------------------------------------------------------------
 typedef unsigned char BYTE;
@@ -162,4 +161,3 @@ typedef const char *LPCSTR;
 //---------------------------------------------------------------------------
 void FixCpu(int cpu);
 
-#endif	// os_h