diff --git a/newlib/ChangeLog b/newlib/ChangeLog
index 1afbaf69f..d4f0c5d30 100644
--- a/newlib/ChangeLog
+++ b/newlib/ChangeLog
@@ -1,3 +1,18 @@
+2010-01-14  Corinna Vinschen  <corinna@vinschen.de>
+
+	* libc/stdio/vfprintf.c (_VFPRINTF_R): Just wave bytes invalid in
+	the current charset through.
+
+2010-01-13  Corinna Vinschen  <corinna@vinschen.de>
+
+	* libc/locale/locale.c (lc_ctype_charset): Disable defaulting to
+	"UTF-8" on Cygwin.
+	(lc_message_charset): Ditto.
+	(loadlocale): Disable setting charset of the "C" locale to "UTF-8" on
+	Cygwin.
+	* libc/stdlib/mbtowc_r.c (__mbtowc): Add Cygwin-specific comment.
+	* libc/stdlib/wctomb_r.c (__wctomb): Ditto.
+
 2010-01-11  Sebastian Huber <sebastian.huber@embedded-brains.de>
 
 	* libc/posix/telldir.c (_cleanupdir): Fixed usage of freed memory.
diff --git a/newlib/libc/stdio/vfprintf.c b/newlib/libc/stdio/vfprintf.c
index 773485885..fc33c3027 100644
--- a/newlib/libc/stdio/vfprintf.c
+++ b/newlib/libc/stdio/vfprintf.c
@@ -724,8 +724,13 @@ _DEFUN(_VFPRINTF_R, (data, fp, fmt0, ap),
 	        cp = fmt;
 #ifdef _MB_CAPABLE
 	        while ((n = __mbtowc (data, &wc, fmt, MB_CUR_MAX,
-				      __locale_charset (), &state)) > 0) {
-                    if (wc == '%')
+				      __locale_charset (), &state)) != 0) {
+		    if (n < 0) {
+			/* Wave invalid chars through. */
+			memset (&state, 0, sizeof state);
+			n = 1;
+		    }
+                    else if (wc == '%')
                         break;
                     fmt += n;
 		}