diff --git a/base/applications/calc/calc.h b/base/applications/calc/calc.h
index 702ad47e77d..afbc813d83a 100644
--- a/base/applications/calc/calc.h
+++ b/base/applications/calc/calc.h
@@ -1,10 +1,14 @@
-#ifndef _CALC_H
-#define _CALC_H
+#ifndef __CALC_H__
+#define __CALC_H__
 
-#include <stdarg.h>
-#include <windef.h>
-#include <winuser.h>
+#define WIN32_LEAN_AND_MEAN
+#include <windows.h>
 #include <tchar.h>
+#include <commctrl.h>
+#include <shellapi.h>
+
+#include <stdio.h>
+#include <string.h>
 #include <math.h>
 #include <float.h>
 #include <malloc.h>
@@ -43,6 +47,8 @@
 #define IDC_STATIC  ((DWORD)-1)
 #endif
 
+#define CALC_VERSION        _T("1.12")
+
 #define MAX_CALC_SIZE       256
 
 /*#define USE_KEYBOARD_HOOK*/
@@ -226,8 +232,10 @@ void convert_real_integer(unsigned int base);
 
 INT_PTR CALLBACK AboutDlgProc(HWND hWnd, UINT msg, WPARAM wp, LPARAM lp);
 
+//
+
 void ConvExecute(HWND hWnd);
 void ConvAdjust(HWND hWnd, int n_cat);
 void ConvInit(HWND hWnd);
 
-#endif /* _CALC_H */
+#endif /* __CALC_H__ */
diff --git a/base/applications/calc/winmain.c b/base/applications/calc/winmain.c
index c6723bac187..ad9b5763b4c 100644
--- a/base/applications/calc/winmain.c
+++ b/base/applications/calc/winmain.c
@@ -1,10 +1,24 @@
-#include "calc.h"
+/*
+ * ReactOS Calc (main program)
+ *
+ * Copyright 2007-2017, Carlo Bramini
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+ */
 
-#include <winbase.h>
-#include <wingdi.h>
-#include <winreg.h>
-#include <shellapi.h>
-#include <commctrl.h>
+#include "calc.h"
 
 #define HTMLHELP_PATH(_pt)  TEXT("%systemroot%\\Help\\calc.chm::") TEXT(_pt)