diff --git a/ChangeLog b/ChangeLog
index 5f7ac5767b..4098c468bc 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Fri Apr 29 10:24:51 2011  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* io.c (make_writeconv): do not add textmode newline decorator if any
+	  newline decorator is set already.  fixes #4618, fixes #4619
+
 Fri Apr 29 10:17:42 2011  KOSAKI Motohiro  <kosaki.motohiro@gmail.com>
 
 	* thread.c (lock_func): small cleanup.
diff --git a/io.c b/io.c
index 328abc7ea8..b479f33cd5 100644
--- a/io.c
+++ b/io.c
@@ -789,7 +789,8 @@ make_writeconv(rb_io_t *fptr)
         ecflags = fptr->encs.ecflags;
         ecopts = fptr->encs.ecopts;
 #ifdef TEXTMODE_NEWLINE_DECORATOR_ON_WRITE
-        if (NEED_NEWLINE_DECORATOR_ON_WRITE(fptr))
+	if (NEED_NEWLINE_DECORATOR_ON_WRITE(fptr) &&
+	    !(ecflags & ECONV_NEWLINE_DECORATOR_MASK))
             ecflags |= TEXTMODE_NEWLINE_DECORATOR_ON_WRITE;
 #endif