diff --git a/ChangeLog b/ChangeLog
index 11f0f832c3..aa6f782e52 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Mon Aug 27 13:11:56 2007  Yukihiro Matsumoto  <matz@ruby-lang.org>
+
+	* string.c (tr_trans): wrong condition for mbmaxlen==1 strings.
+	  [ruby-dev:31652]
+
 Mon Aug 27 00:41:13 2007  Yukihiro Matsumoto  <matz@ruby-lang.org>
 
 	* io.c (rb_io_each_byte): caused infinite loop.  [ruby-dev:31652]
diff --git a/string.c b/string.c
index 26ae87a25e..11c80d4618 100644
--- a/string.c
+++ b/string.c
@@ -3264,13 +3264,14 @@ tr_trans(VALUE str, VALUE src, VALUE repl, int sflag)
 	while (s < send) {
 	    VALUE v = rb_hash_aref(hash, INT2FIX(*s));
 	    if (!NIL_P(v)) {
-		if (cflag) {
-		    *s = last;
-		}
-		else {
+		if (!cflag) {
 		    c = FIX2INT(v);
 		    *s = c & 0xff;
+		    modify = 1;
 		}
+	    }
+	    else if (cflag) {
+		*s = last;
 		modify = 1;
 	    }
 	    s++;