diff --git a/ChangeLog b/ChangeLog
index 47efe0077a..40d3ab14ad 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+Sat Dec 24 10:56:32 2011  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* ext/readline/readline.c (readline_readline): check if outstream
+	  is closed to get rid of a bug of readline 6.  [ruby-dev:45043]
+	  [Bug #5803]
+
 Sat Dec 24 06:59:49 2011  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	* test/readline/test_readline.rb (test_line_buffer__point): use
diff --git a/ext/readline/readline.c b/ext/readline/readline.c
index e8f9743426..888f5d847e 100644
--- a/ext/readline/readline.c
+++ b/ext/readline/readline.c
@@ -40,6 +40,10 @@
 #include <unistd.h>
 #endif
 
+#ifdef HAVE_SYS_STAT_H
+#include <sys/stat.h>
+#endif
+
 static VALUE mReadline;
 
 #define EDIT_LINE_LIBRARY_VERSION "EditLine wrapper"
@@ -372,6 +376,13 @@ readline_readline(int argc, VALUE *argv, VALUE self)
     }
 
     if (!isatty(fileno(rl_instream)) && errno == EBADF) rb_raise(rb_eIOError, "closed stdin");
+    if (rl_outstream) {
+	struct stat stbuf;
+	int fd = fileno(rl_outstream);
+	if (fd < 0 || fstat(fd, &stbuf) != 0) {
+	    rb_raise(rb_eIOError, "closed stdout");
+	}
+    }
 
 #ifdef _WIN32
     rl_prep_terminal(1);
diff --git a/test/readline/test_readline.rb b/test/readline/test_readline.rb
index e3a7c5d4ec..0d5efeac01 100644
--- a/test/readline/test_readline.rb
+++ b/test/readline/test_readline.rb
@@ -303,6 +303,16 @@ class TestReadline < Test::Unit::TestCase
     end
   end
 
+  def test_closed_outstream
+    bug5803 = '[ruby-dev:45043]'
+    IO.pipe do |r, w|
+      Readline.input = r
+      Readline.output = w
+      (w << "##\t").close
+      assert_raise(IOError, bug5803) {Readline.readline}
+    end
+  end
+
   private
 
   def replace_stdio(stdin_path, stdout_path)