diff -Naur ruby-2.3.0-cygwin/configure.in ruby-2.3.0/configure.in
--- ruby-2.3.0-cygwin/configure.in	2016-03-10 16:39:24.281580600 +0300
+++ ruby-2.3.0/configure.in	2016-03-10 17:03:13.152209400 +0300
@@ -60,7 +60,7 @@
 
 AC_DEFUN([RUBY_MINGW32],
 [AS_CASE(["$host_os"],
-[cygwin*], [
+[cygwin*|msys*], [
 AC_CACHE_CHECK(for mingw32 environment, rb_cv_mingw32,
 [AC_TRY_CPP([
 #ifndef __MINGW32__
@@ -114,7 +114,7 @@
   AS_CASE(["$build_os"],
           [linux*], [nacl_cv_os_nick=linux],
           [darwin*], [nacl_cv_os_nick=mac],
-          [cygwin*|mingw*], [nacl_cv_os_nick=win],
+          [cygwin*|msys*|mingw*], [nacl_cv_os_nick=win],
           [nacl_cv_os_nick=$build_os])
 
   host="$host_cpu-chromium-$host_os-"
@@ -565,14 +565,14 @@
 ASFLAGS=$ASFLAGS
 AC_SUBST(ASFLAGS)
 
-AS_CASE(["$target_os"],[cygwin*|mingw*], [ac_cv_prog_ac_ct_OBJCOPY=":"])
+AS_CASE(["$target_os"],[cygwin*|msys*|mingw*], [ac_cv_prog_ac_ct_OBJCOPY=":"])
 
 # BSD's ports and MacPorts prefix GNU binutils with 'g'
 AC_CHECK_TOOLS(OBJDUMP, [objdump gobjdump])
 AC_CHECK_TOOLS(OBJCOPY, [objcopy gobjcopy])
 
 AS_CASE(["$target_os"],
-[cygwin*|mingw*], [
+[cygwin*|msys*|mingw*], [
     AC_CHECK_TOOL(WINDRES, windres)
     AC_CHECK_TOOL(DLLWRAP, dllwrap)
     target=`echo $target | sed "s/^$target_cpu-/-/"`
@@ -893,7 +893,7 @@
       # comments.   We  bypass  ANSI   C  mode  for  them.   Otherwise
       # extension libs cannot include those headers.
     ],
-    [cygwin*|darwin*|netbsd*|nacl], [
+    [cygwin*|msys*|darwin*|netbsd*|nacl], [
       # need lgamma_r(), finite()
     ],
     [
@@ -1142,7 +1142,7 @@
 [haiku*], [
 		LIBS="$LIBS" # m lib is include in root
 		],
-[cygwin*], [	ac_cv_header_langinfo_h=yes
+[cygwin*|msys*], [	ac_cv_header_langinfo_h=yes
 		AC_CHECK_FUNCS(cygwin_conv_path)
 		AC_LIBOBJ([langinfo])
 		],
@@ -2345,7 +2345,7 @@
 	    rb_cv_getcwd_malloc=yes,
 	    rb_cv_getcwd_malloc=no,
 	    AS_CASE($target_os,
-		[linux*|darwin*|*bsd|cygwin*|mingw*|mswin*],
+		[linux*|darwin*|*bsd|cygwin*|msys*|mingw*|mswin*],
 		[rb_cv_getcwd_malloc=yes],
 		[rb_cv_getcwd_malloc=no]))])
     AS_IF([test "$rb_cv_getcwd_malloc" = no], [AC_DEFINE(NO_GETCWD_MALLOC, 1)])
@@ -2520,7 +2520,7 @@
     setjmp_prefix=_
     setjmp_suffix=
 elif test "$ac_cv_func_sigsetjmp" = yes; then
-    AS_CASE([$target_os],[solaris*|cygwin*],[setjmp_prefix=],[setjmp_prefix=sig])
+    AS_CASE([$target_os],[solaris*|cygwin*|msys*],[setjmp_prefix=],[setjmp_prefix=sig])
     setjmp_suffix=
 else
     setjmp_prefix=
@@ -3101,7 +3101,7 @@
       # mkmf.rb's have_header() to fail if the desired resource happens to be
       # installed in the /usr/local tree.
       RUBY_APPEND_OPTION(CCDLFLAGS, -fno-common)],
-    [bsdi*|cygwin*|mingw*|aix*|interix*], [ ],
+    [bsdi*|cygwin*|msys*|mingw*|aix*|interix*], [ ],
     [
       RUBY_APPEND_OPTION(CCDLFLAGS, -fPIC)])
   else
@@ -3203,9 +3203,9 @@
 			: ${LDSHARED='$(LD) -Bshareable -x'}
 			LDFLAGS="$LDFLAGS -L/lib -L/usr/lib -L/usr/local/lib"
 			rb_cv_dlopen=yes],
-	[cygwin*|mingw*], [
+	[cygwin*|msys*|mingw*], [
 			: ${LDSHARED='$(CC) -shared $(if $(filter-out -g -g0,$(debugflags)),,-s)'}
-			XLDFLAGS="$XLDFLAGS -Wl,--stack,0x00200000,--enable-auto-import"
+			XLDFLAGS="$XLDFLAGS -Xlinker --stack -Xlinker 0x00200000,0x00040000 -Xlinker --enable-auto-import"
 			DLDFLAGS="${DLDFLAGS} -Wl,--enable-auto-image-base,--enable-auto-import"
 			: ${LIBPATHENV=""}
 			: ${PRELOADENV=""}
@@ -3577,7 +3577,7 @@
 SOLIBS=
 
 AS_CASE(["$target_os"],
-  [cygwin*|mingw*|haiku*|darwin*], [
+  [cygwin*|msys*|mingw*|haiku*|darwin*], [
     : ${DLDLIBS=""}
     ],
   [
@@ -3923,7 +3923,7 @@
 	  CFLAGS="$CFLAGS -std"
 	fi
 	],
-    [cygwin*|mingw*], [
+    [cygwin*|msys*|mingw*], [
 	RUBY_SO_NAME="${RUBY_SO_NAME}"'$(MAJOR)$(MINOR)$(TEENY)'
 	LIBRUBY_DLDFLAGS="${DLDFLAGS}"' -Wl,--out-implib=$(LIBRUBY)'
 	AS_CASE(["$target_os"],
@@ -3933,6 +3933,12 @@
 		LIBRUBY_DLDFLAGS="${LIBRUBY_DLDFLAGS}"' $(RUBYDEF)'
 	    fi
 	    ],
+	[msys*], [
+	    if test x"$enable_shared" = xyes; then
+		LIBRUBY_SO='msys-$(RUBY_SO_NAME)'.dll
+		LIBRUBY_DLDFLAGS="${LIBRUBY_DLDFLAGS}"' $(RUBYDEF)'
+	    fi
+	    ],
 	[mingw*], [
 	    RUBY_SO_NAME="${rb_cv_msvcrt}-${RUBY_SO_NAME}"
 	    if test x"${target_cpu}" != xi386; then
diff -Naur ruby-2.3.0-cygwin/cygwin/GNUmakefile.in ruby-2.3.0/cygwin/GNUmakefile.in
--- ruby-2.3.0-cygwin/cygwin/GNUmakefile.in	2015-08-26 08:21:41.000000000 +0300
+++ ruby-2.3.0/cygwin/GNUmakefile.in	2016-03-10 16:47:46.285862100 +0300
@@ -6,6 +6,8 @@
 
 ifeq (@target_os@,cygwin)
   DLL_BASE_NAME := $(LIBRUBY_SO:.dll=)
+else ifeq (@target_os@,msys)
+  DLL_BASE_NAME := $(LIBRUBY_SO:.dll=)
 else
   DLL_BASE_NAME := $(RUBY_SO_NAME)
   DLLWRAP += -mno-cygwin
@@ -104,6 +106,12 @@
 	$(ECHO) generating $@
 	$(Q) @DLLWRAP@ -s --def=$(RUBYDEF) -o $@
 endif
+
+ifeq (@target_os@,msys)
+msys2-$(RUBY_INSTALL_NAME)$(MAJOR)$(MINOR)$(TEENY).dll: $(LIBRUBY_A) $(RUBYDEF)
+	$(ECHO) generating $@
+	$(Q) @DLLWRAP@ -s --def=$(RUBYDEF) -o $@
+endif
 
 clean-local::
 	@$(RM) $(RUBY_EXP) $(RCFILES:.rc=.res.@OBJEXT@)
diff -Naur ruby-2.3.0-cygwin/ext/etc/extconf.rb ruby-2.3.0/ext/etc/extconf.rb
--- ruby-2.3.0-cygwin/ext/etc/extconf.rb	2015-12-16 08:31:54.000000000 +0300
+++ ruby-2.3.0/ext/etc/extconf.rb	2016-03-10 16:49:32.065283100 +0300
@@ -34,7 +34,7 @@
   $defs.push("-DPW_AGE2VAL="+f)
 end
 have_struct_member('struct passwd', 'pw_class', 'pwd.h')
-have_struct_member('struct passwd', 'pw_comment', 'pwd.h') unless /cygwin/ === RUBY_PLATFORM
+have_struct_member('struct passwd', 'pw_comment', 'pwd.h') unless /cygwin|msys/ === RUBY_PLATFORM
 have_struct_member('struct passwd', 'pw_expire', 'pwd.h')
 have_struct_member('struct passwd', 'pw_passwd', 'pwd.h')
 have_struct_member('struct group', 'gr_passwd', 'grp.h')
diff -Naur ruby-2.3.0-cygwin/ext/readline/extconf.rb ruby-2.3.0/ext/readline/extconf.rb
--- ruby-2.3.0-cygwin/ext/readline/extconf.rb	2015-12-16 08:31:54.000000000 +0300
+++ ruby-2.3.0/ext/readline/extconf.rb	2016-03-10 16:47:46.344856200 +0300
@@ -30,7 +30,7 @@
 dir_config("readline")
 enable_libedit = enable_config("libedit")
 
-have_library("user32", nil) if /cygwin/ === RUBY_PLATFORM
+have_library("user32", nil) if /cygwin|msys/ === RUBY_PLATFORM
 have_library("ncurses", "tgetnum") ||
   have_library("termcap", "tgetnum") ||
   have_library("curses", "tgetnum")
diff -Naur ruby-2.3.0-cygwin/ext/Setup.nt ruby-2.3.0/ext/Setup.nt
--- ruby-2.3.0-cygwin/ext/Setup.nt	2015-12-20 14:54:54.000000000 +0300
+++ ruby-2.3.0/ext/Setup.nt	2016-03-10 17:04:34.109014800 +0300
@@ -1,4 +1,4 @@
-#option platform cygwin|mingw|mswin
+#option platform cygwin|msys|mingw|mswin
 #option nodynamic
 
 Win32API
diff -Naur ruby-2.3.0-cygwin/ext/socket/extconf.rb ruby-2.3.0/ext/socket/extconf.rb
--- ruby-2.3.0-cygwin/ext/socket/extconf.rb	2015-12-16 08:31:54.000000000 +0300
+++ ruby-2.3.0/ext/socket/extconf.rb	2016-03-10 16:47:46.387851900 +0300
@@ -254,7 +254,7 @@
     # [ruby-dev:44189]
     # http://bugs.ruby-lang.org/issues/5075
     close_fds = false
-  when /cygwin/
+  when /cygwin|msys/
     # Cygwin doesn't support fd passing.
     # http://cygwin.com/ml/cygwin/2003-09/msg01808.html
     close_fds = false
@@ -434,7 +434,7 @@
 when /mswin(32|64)|mingw/
   test_func = "WSACleanup"
   have_library("ws2_32", "WSACleanup", headers)
-when /cygwin/
+when /cygwin|msys/
   test_func = "socket(0,0,0)"
 when /haiku/
   test_func = "socket(0,0,0)"
diff -Naur ruby-2.3.0-cygwin/ext/tk/extconf.rb ruby-2.3.0/ext/tk/extconf.rb
--- ruby-2.3.0-cygwin/ext/tk/extconf.rb	2016-03-10 16:39:24.024606300 +0300
+++ ruby-2.3.0/ext/tk/extconf.rb	2016-03-10 16:47:46.429847700 +0300
@@ -554,7 +554,7 @@
   exts = [CONFIG['DLEXT']]
   exts.concat %w(dll) if is_win32?
   exts.concat %w(bundle dylib) if is_macosx?
-  exts.concat %w(dll.a) if /cygwin/ =~ RUBY_PLATFORM
+  exts.concat %w(dll.a) if /cygwin|msys/ =~ RUBY_PLATFORM
 
   if TkLib_Config["tcltk-stubs"] || TkLib_Config['enable-shared'] == false
     exts.unshift "lib" if is_win32?
diff -Naur ruby-2.3.0-cygwin/ext/tk/lib/tk.rb ruby-2.3.0/ext/tk/lib/tk.rb
--- ruby-2.3.0-cygwin/ext/tk/lib/tk.rb	2015-12-16 08:31:54.000000000 +0300
+++ ruby-2.3.0/ext/tk/lib/tk.rb	2016-03-10 16:47:46.462844400 +0300
@@ -1181,7 +1181,7 @@
       if WITH_RUBY_VM ### check Ruby 1.9 !!!!!!!
         # *** NEED TO FIX ***
         case RUBY_PLATFORM
-        when /cygwin/
+        when /cygwin|msys/
           RUN_EVENTLOOP_ON_MAIN_THREAD = true
         when /darwin/ # MacOS X
 =begin
diff -Naur ruby-2.3.0-cygwin/ext/tk/old-extconf.rb ruby-2.3.0/ext/tk/old-extconf.rb
--- ruby-2.3.0-cygwin/ext/tk/old-extconf.rb	2015-12-16 08:31:54.000000000 +0300
+++ ruby-2.3.0/ext/tk/old-extconf.rb	2016-03-10 16:47:46.517838900 +0300
@@ -3,7 +3,7 @@
 
 require 'mkmf'
 
-is_win32 = (/mswin|mingw|cygwin|bccwin/ =~ RUBY_PLATFORM)
+is_win32 = (/mswin|mingw|cygwin|msys|bccwin/ =~ RUBY_PLATFORM)
 #is_macosx = (/darwin/ =~ RUBY_PLATFORM)
 
 have_func("ruby_native_thread_p", "ruby.h")
@@ -406,7 +406,7 @@
            find_tcl(tcllib, stubs, tclver, *tcl_ldir_list) &&
            find_tk(tklib, stubs, tkver, *tk_ldir_list) ) )
   $CPPFLAGS += ' -DUSE_TCL_STUBS -DUSE_TK_STUBS' if stubs
-  $CPPFLAGS += ' -D_WIN32' if /cygwin/ =~ RUBY_PLATFORM
+  $CPPFLAGS += ' -D_WIN32' if /cygwin|msys/ =~ RUBY_PLATFORM
 
   if tcltk_framework
     if tcl_framework_header
diff -Naur ruby-2.3.0-cygwin/ext/win32/extconf.rb ruby-2.3.0/ext/win32/extconf.rb
--- ruby-2.3.0-cygwin/ext/win32/extconf.rb	2015-12-16 08:31:54.000000000 +0300
+++ ruby-2.3.0/ext/win32/extconf.rb	2016-03-10 16:51:43.760946400 +0300
@@ -1,4 +1,4 @@
 # frozen_string_literal: false
-if compiled?('fiddle') and $mswin||$mingw||$cygwin
+if compiled?('fiddle') and $mswin||$mingw||$cygwin||$msys
   create_makefile('win32')
 end
diff -Naur ruby-2.3.0-cygwin/ext/win32ole/extconf.rb ruby-2.3.0/ext/win32ole/extconf.rb
--- ruby-2.3.0-cygwin/ext/win32ole/extconf.rb	2015-12-16 08:31:54.000000000 +0300
+++ ruby-2.3.0/ext/win32ole/extconf.rb	2016-03-10 16:47:46.581832500 +0300
@@ -6,7 +6,7 @@
 require 'mkmf'
 
 case RUBY_PLATFORM
-when /cygwin/
+when /cygwin|msys/
   inc = nil
   lib = '/usr/lib/w32api'
 end
diff -Naur ruby-2.3.0-cygwin/gems/rake-10.4.2/lib/rake/application.rb ruby-2.3.0/gems/rake-10.4.2/lib/rake/application.rb
--- ruby-2.3.0-cygwin/gems/rake-10.4.2/lib/rake/application.rb	2015-12-24 19:44:59.000000000 +0300
+++ ruby-2.3.0/gems/rake-10.4.2/lib/rake/application.rb	2016-03-10 17:05:30.300774200 +0300
@@ -346,7 +346,7 @@
 
     def unix? # :nodoc:
       RbConfig::CONFIG['host_os'] =~
-        /(aix|darwin|linux|(net|free|open)bsd|cygwin|solaris|irix|hpux)/i
+        /(aix|darwin|linux|(net|free|open)bsd|cygwin|msys|solaris|irix|hpux)/i
     end
 
     def windows? # :nodoc:
diff -Naur ruby-2.3.0-cygwin/lib/mkmf.rb ruby-2.3.0/lib/mkmf.rb
--- ruby-2.3.0-cygwin/lib/mkmf.rb	2015-12-16 12:25:48.000000000 +0300
+++ ruby-2.3.0/lib/mkmf.rb	2016-03-10 16:47:46.665824100 +0300
@@ -132,6 +132,7 @@
   $bccwin = /bccwin/ =~ RUBY_PLATFORM
   $mingw = /mingw/ =~ RUBY_PLATFORM
   $cygwin = /cygwin/ =~ RUBY_PLATFORM
+  $msys = /msys/ =~ RUBY_PLATFORM
   $netbsd = /netbsd/ =~ RUBY_PLATFORM
   $haiku = /haiku/ =~ RUBY_PLATFORM
   $solaris = /solaris/ =~ RUBY_PLATFORM
@@ -1876,6 +1877,12 @@
           IO.popen(["cygpath", "-u", path], &:read).chomp
         end
       end
+    when 'msys'
+      if CONFIG['target_os'] != 'msys'
+        def mkintpath(path)
+          IO.popen(["cygpath", "-u", path], &:read).chomp
+        end
+      end
     end
   end
   unless method_defined?(:mkintpath)
@@ -1892,7 +1899,7 @@
 SHELL = /bin/sh
 
 # V=0 quiet, V=1 verbose.  other values don't work.
-V = 0
+V = 1
 Q1 = $(V:1=)
 Q = $(Q1:0=@)
 ECHO1 = $(V:1=@#{CONFIG['NULLCMD']})
diff -Naur ruby-2.3.0-cygwin/lib/resolv.rb ruby-2.3.0/lib/resolv.rb
--- ruby-2.3.0-cygwin/lib/resolv.rb	2015-11-10 14:48:14.000000000 +0300
+++ ruby-2.3.0/lib/resolv.rb	2016-03-10 16:53:23.147946400 +0300
@@ -168,7 +168,7 @@
 
   class Hosts
     begin
-      raise LoadError unless /mswin|mingw|cygwin/ =~ RUBY_PLATFORM
+      raise LoadError unless /mswin/ =~ RUBY_PLATFORM
       require 'win32/resolv'
       DefaultFileName = Win32::Resolv.get_hosts_path
     rescue LoadError
@@ -967,7 +967,7 @@
         if File.exist? filename
           config_hash = Config.parse_resolv_conf(filename)
         else
-          if /mswin|cygwin|mingw|bccwin/ =~ RUBY_PLATFORM
+          if /mswin|bccwin/ =~ RUBY_PLATFORM
             require 'win32/resolv'
             search, nameserver = Win32::Resolv.get_resolv_info
             config_hash = {}
diff -Naur ruby-2.3.0-cygwin/lib/rubygems/platform.rb ruby-2.3.0/lib/rubygems/platform.rb
--- ruby-2.3.0-cygwin/lib/rubygems/platform.rb	2015-12-16 08:07:31.000000000 +0300
+++ ruby-2.3.0/lib/rubygems/platform.rb	2016-03-10 16:53:23.194946400 +0300
@@ -79,6 +79,7 @@
       @os, @version = case os
                       when /aix(\d+)?/ then             [ 'aix',       $1  ]
                       when /cygwin/ then                [ 'cygwin',    nil ]
+                      when /msys/ then                  [ 'msys',      nil ]
                       when /darwin(\d+)?/ then          [ 'darwin',    $1  ]
                       when /^macruby$/ then             [ 'macruby',   nil ]
                       when /freebsd(\d+)?/ then         [ 'freebsd',   $1  ]
diff -Naur ruby-2.3.0-cygwin/test/dbm/test_dbm.rb.rej ruby-2.3.0/test/dbm/test_dbm.rb.rej
--- ruby-2.3.0-cygwin/test/dbm/test_dbm.rb.rej	1970-01-01 03:00:00.000000000 +0300
+++ ruby-2.3.0/test/dbm/test_dbm.rb.rej	2016-03-10 16:53:23.242946400 +0300
@@ -0,0 +1,16 @@
+--- test/dbm/test_dbm.rb	2013-06-19 11:47:31.000000000 +0400
++++ test/dbm/test_dbm.rb	2014-05-13 12:23:06.187800000 +0400
+@@ -21,6 +21,13 @@
+         raise 'cannot get system name' if uname.call(utsname) == -1
+ 
+         utsname.unpack('A20' * 5)[0]
++      when 'msys'
++        require 'Win32API'
++        uname = Win32API.new('msys-2.0', 'uname', 'P', 'I')
++        utsname = ' ' * 100
++        raise 'cannot get system name' if uname.call(utsname) == -1
++
++        utsname.unpack('A21' * 5)[0]
+       else
+         RbConfig::CONFIG['target_os']
+       end
diff -Naur ruby-2.3.0-cygwin/test/fiddle/helper.rb ruby-2.3.0/test/fiddle/helper.rb
--- ruby-2.3.0-cygwin/test/fiddle/helper.rb	2015-12-16 08:07:31.000000000 +0300
+++ ruby-2.3.0/test/fiddle/helper.rb	2016-03-10 16:53:25.421946400 +0300
@@ -10,6 +10,9 @@
 when /cygwin/
   libc_so = "cygwin1.dll"
   libm_so = "cygwin1.dll"
+when /msys/
+  libc_so = "msys-2.0.dll"
+  libm_so = "msys-2.0.dll"
 when /x86_64-linux/
   libc_so = "/lib64/libc.so.6"
   libm_so = "/lib64/libm.so.6"
diff -Naur ruby-2.3.0-cygwin/test/gdbm/test_gdbm.rb ruby-2.3.0/test/gdbm/test_gdbm.rb
--- ruby-2.3.0-cygwin/test/gdbm/test_gdbm.rb	2015-12-16 08:07:31.000000000 +0300
+++ ruby-2.3.0/test/gdbm/test_gdbm.rb	2016-03-10 16:57:18.358946400 +0300
@@ -15,6 +15,9 @@
       case RbConfig::CONFIG['target_os']
       when 'cygwin'
         require 'etc'
+	Etc.uname[:sysname
+      when 'msys'
+        require 'etc'
 	Etc.uname[:sysname]
       else
         RbConfig::CONFIG['target_os']
diff -Naur ruby-2.3.0-cygwin/test/ruby/test_argf.rb ruby-2.3.0/test/ruby/test_argf.rb
--- ruby-2.3.0-cygwin/test/ruby/test_argf.rb	2015-12-16 08:07:31.000000000 +0300
+++ ruby-2.3.0/test/ruby/test_argf.rb	2016-03-10 16:53:25.481946400 +0300
@@ -54,7 +54,7 @@
   end
 
   def no_safe_rename
-    /cygwin|mswin|mingw|bccwin/ =~ RUBY_PLATFORM
+    /cygwin|msys|mswin|mingw|bccwin/ =~ RUBY_PLATFORM
   end
 
   def assert_src_expected(line, src, args = nil)
diff -Naur ruby-2.3.0-cygwin/test/ruby/test_file_exhaustive.rb ruby-2.3.0/test/ruby/test_file_exhaustive.rb
--- ruby-2.3.0-cygwin/test/ruby/test_file_exhaustive.rb	2015-12-16 08:07:31.000000000 +0300
+++ ruby-2.3.0/test/ruby/test_file_exhaustive.rb	2016-03-10 16:58:18.691946400 +0300
@@ -6,8 +6,8 @@
 
 class TestFileExhaustive < Test::Unit::TestCase
   DRIVE = Dir.pwd[%r'\A(?:[a-z]:|//[^/]+/[^/]+)'i]
-  POSIX = /cygwin|mswin|bccwin|mingw|emx/ !~ RUBY_PLATFORM
-  NTFS = !(/cygwin|mingw|mswin|bccwin/ !~ RUBY_PLATFORM)
+  POSIX = /cygwin|msys|mswin|bccwin|mingw|emx/ !~ RUBY_PLATFORM
+  NTFS = !(/cygwin|msys|mingw|mswin|bccwin/ !~ RUBY_PLATFORM)
 
   def assert_incompatible_encoding
     d = "\u{3042}\u{3044}".encode("utf-16le")
@@ -1155,7 +1155,7 @@
     assert_equal(true, test(?=, fn1, fn1))
     assert_equal(false, test(?>, fn1, fn1))
     assert_equal(false, test(?<, fn1, fn1))
-    unless /cygwin/ =~ RUBY_PLATFORM
+    unless /cygwin|msys/ =~ RUBY_PLATFORM
       assert_equal(false, test(?=, fn1, fn2))
       assert_equal(false, test(?>, fn1, fn2))
       assert_equal(true, test(?>, fn2, fn1))
diff -Naur ruby-2.3.0-cygwin/test/ruby/test_path.rb ruby-2.3.0/test/ruby/test_path.rb
--- ruby-2.3.0-cygwin/test/ruby/test_path.rb	2015-12-16 08:07:31.000000000 +0300
+++ ruby-2.3.0/test/ruby/test_path.rb	2016-03-10 16:53:25.561946400 +0300
@@ -48,7 +48,7 @@
   end
 
   def test_dirname
-    if /(bcc|ms)win\d|mingw|cygwin|emx/ =~ RUBY_PLATFORM
+    if /(bcc|ms)win\d|mingw|cygwin|msys|emx/ =~ RUBY_PLATFORM
       # DOSISH_DRIVE_LETTER
       assert_equal('C:.', File.dirname('C:'))
       assert_equal('C:.', File.dirname('C:a'))
@@ -104,7 +104,7 @@
     assert_equal('/', File.dirname('/a/'))
     assert_equal('/a', File.dirname('/a/b'))
 
-    if /(bcc|ms|cyg)win|mingw|emx/ =~ RUBY_PLATFORM
+    if /(bcc|ms|cyg)win|msys|mingw|emx/ =~ RUBY_PLATFORM
       # DOSISH_UNC
       assert_equal('//', File.dirname('//'))
       assert_equal('//a', File.dirname('//a'))
@@ -138,7 +138,7 @@
   end
 
   def test_basename
-    if /(bcc|ms)win\d|mingw|cygwin|emx/ =~ RUBY_PLATFORM
+    if /(bcc|ms)win\d|mingw|cygwin|msys|emx/ =~ RUBY_PLATFORM
       # DOSISH_DRIVE_LETTER
       assert_equal('', File.basename('C:'))
       assert_equal('a', File.basename('C:a'))
@@ -194,7 +194,7 @@
 
     assert_equal("..", File.basename("..", ".*"))
 
-    if /(bcc|ms|cyg)win|mingw|emx/ =~ RUBY_PLATFORM
+    if /(bcc|ms|cyg)win|msys|mingw|emx/ =~ RUBY_PLATFORM
       # DOSISH_UNC
       assert_equal('/', File.basename('//'))
       assert_equal('/', File.basename('//a'))
diff -Naur ruby-2.3.0-cygwin/test/ruby/test_require.rb ruby-2.3.0/test/ruby/test_require.rb
--- ruby-2.3.0-cygwin/test/ruby/test_require.rb	2015-12-16 08:07:31.000000000 +0300
+++ ruby-2.3.0/test/ruby/test_require.rb	2016-03-10 16:53:25.589946400 +0300
@@ -75,7 +75,7 @@
   end
 
   case RUBY_PLATFORM
-  when /cygwin/, /mswin/, /mingw/, /darwin/
+  when /cygwin/, /msys/, /mswin/, /mingw/, /darwin/
     def self.ospath_encoding(path)
       Encoding::UTF_8
     end
diff -Naur ruby-2.3.0-cygwin/test/rubygems/test_gem_platform.rb ruby-2.3.0/test/rubygems/test_gem_platform.rb
--- ruby-2.3.0-cygwin/test/rubygems/test_gem_platform.rb	2015-12-16 08:07:31.000000000 +0300
+++ ruby-2.3.0/test/rubygems/test_gem_platform.rb	2016-03-10 16:53:25.617946400 +0300
@@ -46,6 +46,7 @@
       'universal-darwin9'      => ['universal', 'darwin',    '9'],
       'universal-macruby'      => ['universal', 'macruby',   nil],
       'i386-cygwin'            => ['x86',       'cygwin',    nil],
+      'i386-msys'              => ['x86',       'msys',      nil],
       'i686-darwin'            => ['x86',       'darwin',    nil],
       'i686-darwin8.4.1'       => ['x86',       'darwin',    '8'],
       'i386-freebsd4.11'       => ['x86',       'freebsd',   '4'],
diff -Naur ruby-2.3.0-cygwin/test/socket/test_addrinfo.rb ruby-2.3.0/test/socket/test_addrinfo.rb
--- ruby-2.3.0-cygwin/test/socket/test_addrinfo.rb	2015-11-14 16:15:33.000000000 +0300
+++ ruby-2.3.0/test/socket/test_addrinfo.rb	2016-03-10 16:53:25.654946400 +0300
@@ -8,7 +8,7 @@
 require "test/unit"
 
 class TestSocketAddrinfo < Test::Unit::TestCase
-  HAS_UNIXSOCKET = defined?(UNIXSocket) && /cygwin/ !~ RUBY_PLATFORM
+  HAS_UNIXSOCKET = defined?(UNIXSocket) && /cygwin|msys/ !~ RUBY_PLATFORM
 
   def tcp_unspecified_to_loopback(addrinfo)
     if addrinfo.ipv4? && addrinfo.ip_address == "0.0.0.0"
diff -Naur ruby-2.3.0-cygwin/test/socket/test_unix.rb ruby-2.3.0/test/socket/test_unix.rb
--- ruby-2.3.0-cygwin/test/socket/test_unix.rb	2015-12-07 21:39:47.000000000 +0300
+++ ruby-2.3.0/test/socket/test_unix.rb	2016-03-10 17:08:29.841904600 +0300
@@ -699,4 +699,4 @@
       assert_equal :wait_readable, serv.accept_nonblock(exception: false)
     }
   end
-end if defined?(UNIXSocket) && /cygwin/ !~ RUBY_PLATFORM
+end if defined?(UNIXSocket) && /cygwin|msys/ !~ RUBY_PLATFORM
diff -Naur ruby-2.3.0-cygwin/test/webrick/test_cgi.rb ruby-2.3.0/test/webrick/test_cgi.rb
--- ruby-2.3.0-cygwin/test/webrick/test_cgi.rb	2015-12-16 08:07:31.000000000 +0300
+++ ruby-2.3.0/test/webrick/test_cgi.rb	2016-03-10 17:00:29.907946400 +0300
@@ -21,7 +21,7 @@
         end
       },
     }
-    if RUBY_PLATFORM =~ /mswin|mingw|cygwin|bccwin32/
+    if RUBY_PLATFORM =~ /mswin|mingw|cygwin|msys|bccwin32/
       config[:CGIPathEnv] = ENV['PATH'] # runtime dll may not be in system dir.
     end
     TestWEBrick.start_httpserver(config, log_tester){|server, addr, port, log|
@@ -38,7 +38,7 @@
       http.request(req){|res| assert_equal("/path/info", res.body, log.call)}
       req = Net::HTTP::Get.new("/webrick.cgi/%3F%3F%3F?foo=bar")
       http.request(req){|res| assert_equal("/???", res.body, log.call)}
-      unless RUBY_PLATFORM =~ /mswin|mingw|cygwin|bccwin32/
+      unless RUBY_PLATFORM =~ /mswin|mingw|cygwin|msys|bccwin32/
         # Path info of res.body is passed via ENV.
         # ENV[] returns different value on Windows depending on locale.
         req = Net::HTTP::Get.new("/webrick.cgi/%A4%DB%A4%B2/%A4%DB%A4%B2")
diff -Naur ruby-2.3.0-cygwin/tool/config.guess ruby-2.3.0/tool/config.guess
--- ruby-2.3.0-cygwin/tool/config.guess	2015-12-24 19:38:18.000000000 +0300
+++ ruby-2.3.0/tool/config.guess	2016-03-10 16:53:25.762946400 +0300
@@ -881,6 +881,9 @@
     amd64:CYGWIN*:*:* | x86_64:CYGWIN*:*:*)
 	echo x86_64-unknown-cygwin
 	exit ;;
+    amd64:MSYS*:*:* | x86_64:MSYS*:*:*)
+	echo x86_64-unknown-msys
+	exit ;;
     p*:CYGWIN*:*)
 	echo powerpcle-unknown-cygwin
 	exit ;;
diff -Naur ruby-2.3.0-cygwin/win32/mkexports.rb ruby-2.3.0/win32/mkexports.rb
--- ruby-2.3.0-cygwin/win32/mkexports.rb	2015-02-23 10:05:23.000000000 +0300
+++ ruby-2.3.0/win32/mkexports.rb	2016-03-10 16:53:25.790946400 +0300
@@ -160,6 +160,30 @@
   end
 end
 
+class Exports::Msys < Exports
+  def self.nm
+    @@nm ||= RbConfig::CONFIG["NM"]
+  end
+
+  def exports(*)
+    super()
+  end
+
+  def each_line(objs, &block)
+    IO.foreach("|#{self.class.nm} --extern --defined #{objs.join(' ')}", &block)
+  end
+
+  def each_export(objs)
+    symprefix = RbConfig::CONFIG["SYMBOL_PREFIX"]
+    symprefix.strip! if symprefix
+    re = /\s(?:(T)|[[:upper:]])\s#{symprefix}((?!Init_|.*_threadptr_|DllMain\b).*)$/
+    objdump(objs) do |l|
+      next if /@.*@/ =~ l
+      yield $2, !$1 if re =~ l
+    end
+  end
+end
+
 class Exports::Mingw < Exports::Cygwin
   def each_export(objs)
     super