diff -du less.orig/defines.wn less/defines.wn
--- less.orig/defines.wn	2011-04-10 06:59:14.000000000 +0100
+++ less/defines.wn	2012-03-15 08:32:53.848812020 +0000
@@ -223,7 +223,11 @@
 /* Define MUST_DEFINE_ERRNO if you have errno but it is not define 
  * in errno.h */
 #define HAVE_ERRNO 1
+#if defined(__MINGW32__) 
+#define MUST_DEFINE_ERRNO 0
+#else
 #define MUST_DEFINE_ERRNO 1
+#endif
 
 /* Define HAVE_SYS_ERRLIST if you have the sys_errlist[] variable */
 #define HAVE_SYS_ERRLIST 1
@@ -326,14 +330,18 @@
 #define HAVE_UNISTD_H 0
 
 /* Define if you have the <values.h> header file.  */
-#ifdef _MSC_VER
+#if defined(_MSC_VER) || defined(__MINGW32__)
 #define HAVE_VALUES_H 0
 #else
 #define HAVE_VALUES_H 1
 #endif
 
+#if !defined(__MINGW32__)
 #define	popen	_popen
 #define	pclose	_pclose
 #define snprintf	_snprintf
+#endif
 
+#if defined(_MSC_VER)
 #pragma warning(disable:4996)
+#endif
diff -du less.orig/filename.c less/filename.c
--- less.orig/filename.c	2011-04-11 23:04:22.000000000 +0100
+++ less/filename.c	2012-03-15 08:23:13.949936491 +0000
@@ -18,7 +18,7 @@
 #include "lglob.h"
 #if MSDOS_COMPILER
 #include <dos.h>
-#if MSDOS_COMPILER==WIN32C && !defined(_MSC_VER)
+#if MSDOS_COMPILER==WIN32C && defined(__BORLANDC__)
 #include <dir.h>
 #endif
 #if MSDOS_COMPILER==DJGPPC
@@ -563,7 +563,9 @@
 
 #if HAVE_POPEN
 
+#if MSDOS_COMPILER && MSDOS_COMPILER!=WIN32C
 FILE *popen();
+#endif
 
 /*
  * Execute a shell command.
diff -du less.orig/lglob.h less/lglob.h
--- less.orig/lglob.h	2011-01-06 00:30:14.000000000 +0000
+++ less/lglob.h	2012-03-15 08:22:10.401621327 +0000
@@ -57,7 +57,7 @@
 					char ext[_MAX_EXT];	\
 					int handle;
 #else
-#if MSDOS_COMPILER==WIN32C && defined(_MSC_VER)
+#if MSDOS_COMPILER==WIN32C && (defined(_MSC_VER) || defined(__MINGW2__))
 
 #define	GLOB_FIRST_NAME(filename,fndp,h) h = _findfirst(filename, fndp)
 #define	GLOB_FIRST_FAILED(handle)	((handle) == -1)
@@ -73,7 +73,7 @@
 					long handle;
 
 #else
-#if MSDOS_COMPILER==WIN32C && !defined(_MSC_VER) /* Borland C for Windows */
+#if MSDOS_COMPILER==WIN32C && defined(__BORLANDC__) /* Borland C for Windows */
 
 #define	GLOB_FIRST_NAME(filename,fndp,h) h = findfirst(filename, fndp, ~FA_LABEL)
 #define	GLOB_FIRST_FAILED(handle)	((handle) != 0)
diff -du less.orig/lsystem.c less/lsystem.c
--- less.orig/lsystem.c	2011-04-11 23:04:22.000000000 +0100
+++ less/lsystem.c	2012-03-15 08:23:56.518147471 +0000
@@ -20,7 +20,7 @@
 
 #if MSDOS_COMPILER
 #include <dos.h>
-#ifdef _MSC_VER
+#if defined(_MSC_VER) || defined(__MINGW32__)
 #include <direct.h>
 #define setdisk(n) _chdrive((n)+1)
 #else
@@ -292,7 +292,9 @@
 {
 	register FILE *f;
 	register int c;
+#if MSDOS_COMPILER && MSDOS_COMPILER!=WIN32C
 	extern FILE *popen();
+#endif
 
 	/*
 	 * This is structured much like lsystem().