diff --git a/ChangeLog b/ChangeLog
index 0f204143ab..de88f4092f 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,10 @@
+Wed Jul 30 10:31:37 2003  Nobuyoshi Nakada  <nobu.nokada@softhome.net>
+
+	* ext/iconv/iconv.c (iconv_convert): append unchanged portion
+	  after overflow.  [ruby-dev:21006]
+
+	* ext/iconv/extconf.rb: check if iconv() 2nd argument is const.
+
 Wed Jul 30 09:31:55 2003  Nobuyoshi Nakada  <nobu.nokada@softhome.net>
 
 	* configure.in (os2-emx): renamed from os2_emx, add flags to
diff --git a/ext/iconv/extconf.rb b/ext/iconv/extconf.rb
index b81b7379fc..7176fa45e3 100644
--- a/ext/iconv/extconf.rb
+++ b/ext/iconv/extconf.rb
@@ -6,6 +6,20 @@ conf = File.exist?(File.join($srcdir, "config.charset"))
 conf = with_config("config-charset", enable_config("config-charset", conf))
 
 if have_header("iconv.h")
+  if !try_compile("", "-Werror") or checking_for("iconv() 2nd argument is const") do
+      !try_compile('
+#include <iconv.h>
+size_t
+test(iconv_t cd, char **inptr, size_t *inlen, char **outptr, size_t *outlen)
+{
+    return iconv(cd, inptr, inlen, outptr, outlen);
+}
+', "-Werror")
+    end
+    $defs.push('-DICONV_INPTR_CAST=""')
+  else
+    $defs.push('-DICONV_INPTR_CAST="(char **)"')
+  end
   have_library("iconv")
   if conf
     prefix = '$(srcdir)'
diff --git a/ext/iconv/iconv.c b/ext/iconv/iconv.c
index 0ff7e0f7eb..cbb89dca48 100644
--- a/ext/iconv/iconv.c
+++ b/ext/iconv/iconv.c
@@ -209,7 +209,7 @@ iconv_try
     size_t *outlen;
 #endif /* HAVE_PROTOTYPES */
 {
-    if (iconv(cd, (char **)inptr, inlen, outptr, outlen) == (size_t)-1) {
+    if (iconv(cd, ICONV_INPTR_CAST inptr, inlen, outptr, outlen) == (size_t)-1) {
 	if (!*inlen)
 	    return Qfalse;
 	switch (errno) {
@@ -401,6 +401,8 @@ iconv_convert
 
     if (!ret)
 	ret = rb_str_derive(str, instart, inptr - instart);
+    else if (inptr > instart)
+	rb_str_cat(ret, instart, inptr - instart);
     return ret;
 }