diff --git a/ChangeLog b/ChangeLog
index 6ab9cb135f..a1a705bbf5 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+Sun Jul 17 13:46:54 2005  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* ext/io/wait/extconf.rb, ext/io/wait/wait.c: Win32 platforms support.
+
 Sat Jul 16 23:43:16 2005  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	* enumerator.c (Init_Enumerator): wrong argument specs.
diff --git a/ext/io/wait/extconf.rb b/ext/io/wait/extconf.rb
index ea7dc9f6cf..1352ef202e 100644
--- a/ext/io/wait/extconf.rb
+++ b/ext/io/wait/extconf.rb
@@ -3,10 +3,15 @@ target = "io/wait"
 
 unless macro_defined?("DOSISH", "#include <ruby.h>")
   fionread = %w[sys/ioctl.h sys/filio.h].find do |h|
-    checking_for("FIONREAD") {macro_defined?("FIONREAD", "#include <#{h}>\n")}
+    checking_for("FIONREAD") {have_macro("FIONREAD", h)}
   end
   if fionread
     $defs << "-DFIONREAD_HEADER=\"<#{fionread}>\""
     create_makefile(target)
   end
+else
+  if have_func("rb_w32_ioctlsocket", "ruby.h")
+    have_func("rb_w32_is_socket", "ruby.h")
+    create_makefile(target)
+  end
 end
diff --git a/ext/io/wait/wait.c b/ext/io/wait/wait.c
index fcb3bcfe42..25494c0f28 100644
--- a/ext/io/wait/wait.c
+++ b/ext/io/wait/wait.c
@@ -15,7 +15,17 @@
 #include "rubyio.h"
 
 #include <sys/types.h>
+#if defined(FIONREAD_HEADER)
 #include FIONREAD_HEADER
+#elif defined(HAVE_RB_W32_IOCTLSOCKET)
+#define ioctl ioctlsocket
+#endif
+
+#ifdef HAVE_RB_W32_IS_SOCKET
+#define FIONREAD_POSSIBLE_P(fd) rb_w32_is_socket(fptr->fd)
+#else
+#define FIONREAD_POSSIBLE_P(fd) Qtrue
+#endif
 
 static VALUE io_ready_p _((VALUE io));
 static VALUE io_wait _((int argc, VALUE *argv, VALUE io));
@@ -45,6 +55,7 @@ io_ready_p(io)
     GetOpenFile(io, fptr);
     rb_io_check_readable(fptr);
     if (rb_io_read_pending(fptr)) return Qtrue;
+    if (!FIONREAD_POSSIBLE_P(fptr->fd)) return Qfalse;
     if (ioctl(fptr->fd, FIONREAD, &n)) rb_sys_fail(0);
     if (n > 0) return INT2NUM(n);
     return Qnil;
@@ -98,6 +109,7 @@ io_wait(argc, argv, io)
     }
 
     if (rb_io_read_pending(fptr)) return Qtrue;
+    if (!FIONREAD_POSSIBLE_P(fptr->fd)) return Qfalse;
     fd = fptr->fd;
     rb_fd_init(&arg.fds);
     rb_fd_set(fd, &arg.fds);