diff --git a/ChangeLog b/ChangeLog
index 5f1e69a3e4..11bd451833 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,13 @@
+Thu Jun 12 08:47:51 2008  Yukihiro Matsumoto  <matz@ruby-lang.org>
+
+	* io.c (read_all): should use io_read_encoding(), not
+	  io_input_encoding().
+
+	* io.c (rb_io_getline_1): reduce calling of io_read_encoding().
+
+	* string.c (rb_str_scan): need not to restore $~ value, so avoid
+	  pinning match object.
+
 Thu Jun 12 02:49:40 2008  Yusuke Endoh  <mame@tsg.ne.jp>
 
 	* ext/stringio/stringio.c (strio_init): rewind when reopened.
diff --git a/io.c b/io.c
index a53e5589b6..b6815ce40f 100644
--- a/io.c
+++ b/io.c
@@ -1397,7 +1397,7 @@ read_all(rb_io_t *fptr, long siz, VALUE str)
     long bytes = 0;
     long n;
     long pos = 0;
-    rb_encoding *enc = io_input_encoding(fptr);
+    rb_encoding *enc = io_read_encoding(fptr);
     int cr = fptr->enc2 ? ENC_CODERANGE_BROKEN : 0;
 
     if (siz == 0) siz = BUFSIZ;
@@ -1835,12 +1835,11 @@ swallow(rb_io_t *fptr, int term)
 }
 
 static VALUE
-rb_io_getline_fast(rb_io_t *fptr)
+rb_io_getline_fast(rb_io_t *fptr, rb_encoding *enc)
 {
     VALUE str = Qnil;
     int len = 0;
     long pos = 0;
-    rb_encoding *enc = io_input_encoding(fptr);
     int cr = fptr->enc2 ? ENC_CODERANGE_BROKEN : 0;
 
     for (;;) {
@@ -1950,7 +1949,6 @@ rb_io_getline_1(VALUE rs, long limit, VALUE io)
 
     GetOpenFile(io, fptr);
     rb_io_check_readable(fptr);
-    enc = io_input_encoding(fptr);
     if (NIL_P(rs)) {
 	str = read_all(fptr, 0, Qnil);
 	if (RSTRING_LEN(str) == 0) return Qnil;
@@ -1959,8 +1957,8 @@ rb_io_getline_1(VALUE rs, long limit, VALUE io)
 	return rb_enc_str_new(0, 0, io_read_encoding(fptr));
     }
     else if (rs == rb_default_rs && limit < 0 &&
-             rb_enc_asciicompat(io_read_encoding(fptr))) {
-	return rb_io_getline_fast(fptr);
+             rb_enc_asciicompat(enc = io_read_encoding(fptr))) {
+	return rb_io_getline_fast(fptr, enc);
     }
     else {
 	int c, newline;
@@ -1981,6 +1979,7 @@ rb_io_getline_1(VALUE rs, long limit, VALUE io)
 	}
 	newline = rsptr[rslen - 1];
 
+	enc = io_input_encoding(fptr);
 	while ((c = appendline(fptr, newline, &str, &limit)) != EOF) {
 	    if (c == newline) {
 		const char *s, *p, *pp;
@@ -2034,7 +2033,7 @@ rb_io_gets(VALUE io)
 
     GetOpenFile(io, fptr);
     rb_io_check_readable(fptr);
-    return rb_io_getline_fast(fptr);
+    return rb_io_getline_fast(fptr, io_read_encoding(fptr));
 }
 
 /*
diff --git a/string.c b/string.c
index ef54b7e459..d123207fd4 100644
--- a/string.c
+++ b/string.c
@@ -5705,11 +5705,8 @@ rb_str_scan(VALUE str, VALUE pat)
     }
 
     while (!NIL_P(result = scan_once(str, pat, &start))) {
-	match = rb_backref_get();
-	rb_match_busy(match);
 	rb_yield(result);
 	str_mod_check(str, p, len);
-	rb_backref_set(match);	/* restore $~ value */
     }
     rb_backref_set(match);
     return str;