diff --git a/ChangeLog b/ChangeLog
index 5cc31577ce..e3d50533f0 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Fri Oct 22 00:22:31 2004  Yukihiro Matsumoto  <matz@ruby-lang.org>
+
+	* ext/zlib/zlib.c (zstream_shift_buffer): should restore class
+	  field of a buffer.  [ruby-dev:24562]
+
 Fri Oct 22 00:20:33 2004  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	* string.c (rb_str_include): should not treat char as negative value.
@@ -14,6 +19,12 @@ Thu Oct 21 13:11:31 2004  WATANABE Hirofumi  <eban@ruby-lang.org>
 
 Thu Oct 21 00:36:41 2004  Yukihiro Matsumoto  <matz@ruby-lang.org>
 
+	* eval.c (rb_alias): should warn on method discarding.
+	  [ruby-dev:24546]
+
+	* ext/zlib/zlib.c (zstream_expand_buffer_into): hide internal
+	  string buffer by clearing klass.  [ruby-dev:24548]
+
 	* parse.y (lex_getline): should not touch ruby_debug_lines if
 	  RIPPER is defined.  [ruby-dev:24547]
 
diff --git a/eval.c b/eval.c
index a237768145..599e9b4339 100644
--- a/eval.c
+++ b/eval.c
@@ -2016,6 +2016,9 @@ rb_alias(klass, name, def)
     if (FL_TEST(klass, FL_SINGLETON)) {
 	singleton = rb_iv_get(klass, "__attached__");
     }
+    if (RTEST(ruby_verbose) && klass == origin && orig->nd_cnt == 0 && orig->nd_body) {
+	rb_warning("discarding old %s", rb_id2name(name));
+    }
     body = orig->nd_body;
     orig->nd_cnt++;
     if (nd_type(body) == NODE_FBODY) { /* was alias */
diff --git a/ext/zlib/zlib.c b/ext/zlib/zlib.c
index f5fe2e3fa4..aed2a26134 100644
--- a/ext/zlib/zlib.c
+++ b/ext/zlib/zlib.c
@@ -471,6 +471,7 @@ zstream_expand_buffer_into(z, size)
 	z->buf_filled = 0;
 	z->stream.next_out = RSTRING(z->buf)->ptr;
 	z->stream.avail_out = size;
+	RBASIC(z->buf)->klass = 0;
     }
     else if (z->stream.avail_out != size) {
 	rb_str_resize(z->buf, z->buf_filled + size);
@@ -491,6 +492,7 @@ zstream_append_buffer(z, src, len)
 	z->buf_filled = len;
 	z->stream.next_out = RSTRING(z->buf)->ptr;
 	z->stream.avail_out = 0;
+	RBASIC(z->buf)->klass = 0;
 	return;
     }
 
@@ -526,13 +528,13 @@ zstream_detach_buffer(z)
     else {
 	dst = z->buf;
 	rb_str_resize(dst, z->buf_filled);
+	RBASIC(dst)->klass = rb_cString;
     }
 
     z->buf = Qnil;
     z->buf_filled = 0;
     z->stream.next_out = 0;
     z->stream.avail_out = 0;
-    RBASIC(dst)->klass = rb_cString;
     return dst;
 }
 
@@ -548,6 +550,7 @@ zstream_shift_buffer(z, len)
     }
 
     dst = rb_str_substr(z->buf, 0, len);
+    RBASIC(dst)->klass = rb_cString;
     z->buf_filled -= len;
     memmove(RSTRING(z->buf)->ptr, RSTRING(z->buf)->ptr + len,
 	    z->buf_filled);
diff --git a/io.c b/io.c
index 460973ff27..9bdad5496b 100644
--- a/io.c
+++ b/io.c
@@ -1132,11 +1132,13 @@ io_readpartial(argc, argv, io)
 
     READ_CHECK(fptr->f);
     if (RSTRING(str)->len != len) {
+      modified:
 	rb_raise(rb_eRuntimeError, "buffer string modified");
     }
     n = read_buffered_data(RSTRING(str)->ptr, len, fptr->f);
     if (n <= 0) {
       again:
+	if (RSTRING(str)->len != len) goto modified;
         TRAP_BEG;
         n = read(fileno(fptr->f), RSTRING(str)->ptr, len);
         TRAP_END;