diff --git a/include/def_os2.h b/include/def_os2.h
new file mode 100644
index 000000000..58713e576
--- /dev/null
+++ b/include/def_os2.h
@@ -0,0 +1,212 @@
+/*	SCCS Id: @(#)def_os2.h	3.3	93/01/19	*/
+/* Copyright (c) Timo Hakulinen, 1990, 1991, 1992, 1993.	  */
+/* NetHack may be freely redistributed.  See license for details. */
+
+/*
+ *	Only a small portion of all OS/2 defines are needed, so the
+ *	actual include files often need not be used.  In fact,
+ *	including the full headers may stall the compile in DOS.
+ */
+
+#ifdef OS2_USESYSHEADERS
+
+# define INCL_NOPMAPI
+# define INCL_DOSFILEMGR
+# define INCL_DOS
+# define INCL_SUB
+
+#include <os2.h>
+
+#else
+
+typedef char CHAR;
+typedef void VOID;
+
+typedef unsigned char UCHAR;
+typedef unsigned short USHORT;
+typedef unsigned int UINT;
+typedef unsigned long ULONG;
+typedef unsigned char BYTE;
+
+# ifdef OS2_32BITAPI
+
+typedef unsigned long SHANDLE;
+typedef USHORT HKBD;
+typedef USHORT HVIO;
+
+#  define CCHMAXPATHCOMP 256
+
+#  ifdef OS2_CSET2
+#   define API16 _Far16 _Pascal
+#   define DAT16
+#   define API32 _System
+#   define KbdGetStatus KBD16GETSTATUS
+#   define KbdSetStatus KBD16SETSTATUS
+#   define KbdCharIn    KBD16CHARIN
+#   define KbdPeek      KBD16PEEK
+#   define VioGetMode   VIO16GETMODE
+#   define VioSetCurPos VIO16SETCURPOS
+#  else
+#   define API16
+#   define DAT16
+#   define API32
+#  endif
+
+#  define DAT
+
+# else /* OS2_32BITAPI */
+
+typedef unsigned short SHANDLE;
+typedef SHANDLE HKBD;
+typedef SHANDLE HVIO;
+
+#  define CCHMAXPATHCOMP 13
+
+#  ifdef OS2_MSC
+#   define API16 pascal far
+#   define DAT16
+#  endif
+
+#  define DAT DAT16
+
+# endif /* OS2_32BITAPI */
+
+typedef USHORT * DAT16 PUSHORT;
+typedef BYTE * DAT16 PBYTE;
+typedef ULONG * DAT PULONG;
+typedef VOID * DAT PVOID;
+
+typedef SHANDLE HDIR;
+typedef HDIR * DAT PHDIR;
+
+typedef char * DAT16 PCH;
+typedef char * DAT PSZ;
+
+/* all supported compilers understand this */
+
+# pragma pack(2)
+
+typedef struct {
+	UCHAR  chChar;
+	UCHAR  chScan;
+	UCHAR  fbStatus;
+	UCHAR  bNlsShift;
+	USHORT fsState;
+	ULONG  time;
+} KBDKEYINFO;
+
+typedef KBDKEYINFO * DAT16 PKBDKEYINFO;
+
+/* File time and date types */
+
+typedef struct {
+	UINT twosecs : 5;
+	UINT minutes : 6;
+	UINT hours   : 5;
+} FTIME;
+
+typedef struct {
+	UINT day     : 5;
+	UINT month   : 4;
+	UINT year    : 7;
+} FDATE;
+
+# ifdef OS2_32BITAPI
+
+typedef struct {
+	ULONG oNextEntryOffset;
+	FDATE fdateCreation;
+	FTIME ftimeCreation;
+	FDATE fdateLastAccess;
+	FTIME ftimeLastAccess;
+	FDATE fdateLastWrite;
+	FTIME ftimeLastWrite;
+	ULONG cbFile;
+	ULONG cbFileAlloc;
+	ULONG attrFile;
+	UCHAR cchName;
+	CHAR  achName[CCHMAXPATHCOMP];
+} FILEFINDBUF3;
+
+# else
+
+typedef struct {
+	FDATE  fdateCreation;
+	FTIME  ftimeCreation;
+	FDATE  fdateLastAccess;
+	FTIME  ftimeLastAccess;
+	FDATE  fdateLastWrite;
+	FTIME  ftimeLastWrite;
+	ULONG  cbFile;
+	ULONG  cbFileAlloc;
+	USHORT attrFile;
+	UCHAR  cchName;
+	CHAR   achName[CCHMAXPATHCOMP];
+} FILEFINDBUF;
+
+typedef FILEFINDBUF * DAT16 PFILEFINDBUF;
+
+# endif /* OS2_32BITAPI */
+
+typedef struct {
+	ULONG  idFileSystem;
+	ULONG  cSectorUnit;
+	ULONG  cUnit;
+	ULONG  cUnitAvail;
+	USHORT cbSector;
+} FSALLOCATE;
+
+typedef struct {
+	USHORT cb;
+	USHORT fsMask;
+	USHORT chTurnAround;
+	USHORT fsInterim;
+	USHORT fsState;
+} KBDINFO;
+
+typedef KBDINFO * DAT16 PKBDINFO;
+
+typedef struct {
+	USHORT cb;
+	UCHAR  fbType;
+	UCHAR  color;
+	USHORT col;
+	USHORT row;
+	USHORT hres;
+	USHORT vres;
+	UCHAR  fmt_ID;
+	UCHAR  attrib;
+	ULONG  buf_addr;
+	ULONG  buf_length;
+	ULONG  full_length;
+	ULONG  partial_length;
+	PCH    ext_data_addr;
+} VIOMODEINFO;
+
+typedef VIOMODEINFO * DAT16 PVIOMODEINFO;
+
+# pragma pack()
+
+/* OS2 API functions */
+
+USHORT API16 KbdGetStatus(PKBDINFO, HKBD);
+USHORT API16 KbdSetStatus(PKBDINFO, HKBD);
+USHORT API16 KbdCharIn(PKBDKEYINFO, USHORT, HKBD);
+USHORT API16 KbdPeek(PKBDKEYINFO, HKBD);
+
+USHORT API16 VioGetMode(PVIOMODEINFO, HVIO);
+USHORT API16 VioSetCurPos(USHORT, USHORT, HVIO);
+
+# ifdef OS2_32BITAPI
+ULONG API32 DosQueryFSInfo(ULONG, ULONG, PVOID, ULONG);
+ULONG API32 DosFindFirst(PSZ, PHDIR, ULONG, PVOID, ULONG, PULONG, ULONG);
+ULONG API32 DosFindNext(HDIR, PVOID, ULONG, PULONG);
+ULONG API32 DosSetDefaultDisk(ULONG);
+# else
+USHORT API16 DosQFSInfo(USHORT, USHORT, PBYTE, USHORT);
+USHORT API16 DosFindFirst(PSZ, PHDIR, USHORT, PFILEFINDBUF, USHORT, PUSHORT, ULONG);
+USHORT API16 DosFindNext(HDIR, PFILEFINDBUF, USHORT, PUSHORT);
+USHORT API16 DosSelectDisk(USHORT);
+# endif /* OS2_32BITAPI */
+
+#endif /* OS2_USESYSHEADERS */