diff --git a/include/fmt.h b/include/fmt.h
index 480ccad58d..2280f25250 100644
--- a/include/fmt.h
+++ b/include/fmt.h
@@ -1,7 +1,7 @@
 #ifndef _FMT_H_
 #define _FMT_H_ 1
 #if defined(__cplusplus)
-extern "C" { 
+extern "C" {
 #endif
 /*
  * The authors of this software are Rob Pike and Ken Thompson.
@@ -30,7 +30,7 @@ struct Fmt{
 	void	*farg;			/* to make flush a closure */
 	int	nfmt;			/* num chars formatted so far */
 	va_list	args;			/* args passed to dofmt */
-	int	r;			/* % format Rune */
+	Rune	r;			/* % format Rune */
 	int	width;
 	int	prec;
 	unsigned long	flags;
@@ -38,8 +38,8 @@ struct Fmt{
 
 	/* For %'d */
 	char *thousands;	/* separator for thousands */
-	
-	/* 
+
+	/*
 	 * Each char is an integer indicating #digits before next separator. Values:
 	 *	\xFF: no more grouping (or \x7F; defined to be CHAR_MAX in POSIX)
 	 *	\x00: repeat previous indefinitely
diff --git a/src/lib9/fmt/dofmt.c b/src/lib9/fmt/dofmt.c
index ea43940d85..51f0f079b7 100644
--- a/src/lib9/fmt/dofmt.c
+++ b/src/lib9/fmt/dofmt.c
@@ -4,15 +4,15 @@
  *
  *     Copyright (c) 2002-2006 by Lucent Technologies.
  *     Portions Copyright (c) 2004 Google Inc.
- * 
+ *
  * Permission to use, copy, modify, and distribute this software for any
  * purpose without fee is hereby granted, provided that this entire notice
  * is included in all copies of any software which is or includes a copy
  * or modification of this software and in all copies of the supporting
  * documentation for such software.
  * THIS SOFTWARE IS BEING PROVIDED "AS IS", WITHOUT ANY EXPRESS OR IMPLIED
- * WARRANTY.  IN PARTICULAR, NEITHER THE AUTHORS NOR LUCENT TECHNOLOGIES 
- * NOR GOOGLE INC MAKE ANY REPRESENTATION OR WARRANTY OF ANY KIND CONCERNING 
+ * WARRANTY.  IN PARTICULAR, NEITHER THE AUTHORS NOR LUCENT TECHNOLOGIES
+ * NOR GOOGLE INC MAKE ANY REPRESENTATION OR WARRANTY OF ANY KIND CONCERNING
  * THE MERCHANTABILITY OF THIS SOFTWARE OR ITS FITNESS FOR ANY PARTICULAR PURPOSE.
  */
 
@@ -618,12 +618,13 @@ __flagfmt(Fmt *f)
 int
 __badfmt(Fmt *f)
 {
-	char x[3];
+	char x[2+UTFmax];
+	int n;
 
 	x[0] = '%';
-	x[1] = f->r;
-	x[2] = '%';
-	f->prec = 3;
-	__fmtcpy(f, (const void*)x, 3, 3);
+	n = 1 + runetochar(x+1, &f->r);
+	x[n++] = '%';
+	f->prec = n;
+	__fmtcpy(f, (const void*)x, n, n);
 	return 0;
 }
diff --git a/src/lib9/utf/utf.h b/src/lib9/utf/utf.h
index ff5193ad40..1479e9f218 100644
--- a/src/lib9/utf/utf.h
+++ b/src/lib9/utf/utf.h
@@ -18,7 +18,7 @@
 
 #include <stdint.h>
 
-typedef signed int Rune;	/* Code-point values in Unicode 4.0 are 21 bits wide.*/
+typedef unsigned int Rune;	/* Code-point values in Unicode 4.0 are 21 bits wide.*/
 
 enum
 {
diff --git a/src/libbio/bgetrune.c b/src/libbio/bgetrune.c
index caeb0a88ff..1538f3ea74 100644
--- a/src/libbio/bgetrune.c
+++ b/src/libbio/bgetrune.c
@@ -33,7 +33,7 @@ Bgetrune(Biobuf *bp)
 {
 	int c, i;
 	Rune rune;
-	char str[4];
+	char str[UTFmax];
 
 	c = Bgetc(bp);
 	if(c < Runeself) {		/* one char */
diff --git a/src/libbio/bputrune.c b/src/libbio/bputrune.c
index 9c588db9df..e46f3c7101 100644
--- a/src/libbio/bputrune.c
+++ b/src/libbio/bputrune.c
@@ -32,7 +32,7 @@ int
 Bputrune(Biobuf *bp, long c)
 {
 	Rune rune;
-	char str[4];
+	char str[UTFmax];
 	int n;
 
 	rune = c;