diff --git a/ChangeLog b/ChangeLog
index 4b89da51d5..66cfd46dd2 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,11 @@
+Sun Jan 18 23:59:44 2004  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* ext/iconv/charset_alias.rb: prefer us_EN locale encodings or
+	  former.  [ruby-dev:22609]
+
+	* ext/iconv/iconv.c (iconv_create): raise InvalidEncoding
+	  exception when EINVAL.
+
 Sun Jan 18 23:16:34 2004  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	* class.c, error.c, file.c, io.c, numeric.c, object.c, re.c, struct.c,
diff --git a/ext/iconv/charset_alias.rb b/ext/iconv/charset_alias.rb
index be2c1412e7..458dc89d4a 100644
--- a/ext/iconv/charset_alias.rb
+++ b/ext/iconv/charset_alias.rb
@@ -13,10 +13,13 @@ class Hash::Ordered < Hash
   end
   def []=(key, val)
     ary = fetch(key) {return super(key, [self.size, key, val])} and
-      ary.last = val
+      ary << val
   end
-  def each
-    values.sort.each {|i, key, val| yield key, val}
+  def sort
+    values.sort.collect {|i, *rest| rest}
+  end
+  def each(&block)
+    sort.each(&block)
   end
 end
 
@@ -32,17 +35,40 @@ def charset_alias(config_charset, mapfile, target = OS)
   end
   case target
   when /linux|-gnu/
-    map.delete('ascii')
-  when /cygwin/
+#    map.delete('ascii')
+  when /cygwin|os2-emx/
     # get rid of tilde/yen problem.
     map['shift_jis'] = 'cp932'
   end
+  st = Hash.new(0)
+  map = map.sort.collect do |can, *sys|
+    if sys.grep(/^en_us(?=.|$)/i) {break true} == true
+      noen = %r"^(?!en_us)\w+_\w+#{Regexp.new($')}$"i
+      sys.reject! {|s| noen =~ s}
+    end
+    sys = sys.first
+    st[sys] += 1
+    [can, sys]
+  end
+  st.delete_if {|sys, i| i == 1}.empty?
+  st.keys.each {|sys| st[sys] = nil}
+  st.default = nil
   open(mapfile, "w") do |f|
     f.puts("require 'iconv.so'")
     f.puts
     f.puts(comments)
     f.puts("class Iconv")
-    map.each {|can, sys| f.puts("  charset_map['#{can}'.freeze] = '#{sys}'.freeze")}
+    i = 0
+    map.each do |can, sys|
+      if s = st[sys]
+        sys = s
+      elsif st.key?(sys)
+        sys = (st[sys] = "sys#{i+=1}") + " = '#{sys}'.freeze"
+      else
+        sys = "'#{sys}'.freeze"
+      end
+      f.puts("  charset_map['#{can}'.freeze] = #{sys}")
+    end
     f.puts("end")
   end
 end
diff --git a/ext/iconv/iconv.c b/ext/iconv/iconv.c
index 4b1f4b5073..bceb7ca692 100644
--- a/ext/iconv/iconv.c
+++ b/ext/iconv/iconv.c
@@ -53,6 +53,7 @@ struct iconv_env_t
     VALUE (*append)_((VALUE, VALUE));
 };
 
+static VALUE rb_eIconvInvalidEncoding;
 static VALUE rb_eIconvFailure;
 static VALUE rb_eIconvIllegalSeq;
 static VALUE rb_eIconvInvalidChar;
@@ -143,10 +144,15 @@ iconv_create
 	    cd = iconv_open(tocode, fromcode);
 	}
 	if (cd == (iconv_t)-1) {
-	    volatile VALUE msg = rb_str_new2("iconv(\"");
+	    int inval = errno == EINVAL;
+	    volatile VALUE msg = rb_str_new2("iconv(\"" + (inval ? 5 : 0));
+	    char *s;
+
 	    rb_str_buf_cat2(rb_str_buf_append(msg, to), "\", \"");
 	    rb_str_buf_cat2(rb_str_buf_append(msg, from), "\")");
-	    rb_sys_fail(StringValuePtr(msg));
+	    s = StringValuePtr(msg);
+	    if (!inval) rb_sys_fail(s);
+	    rb_raise(rb_eIconvInvalidEncoding, "invalid encoding %s", s);
 	}
     }
 
@@ -847,6 +853,7 @@ Init_iconv _((void))
     rb_define_method(rb_eIconvFailure, "failed", iconv_failure_failed, 0);
     rb_define_method(rb_eIconvFailure, "inspect", iconv_failure_inspect, 0);
 
+    rb_eIconvInvalidEncoding = rb_define_class_under(rb_cIconv, "InvalidEncoding", rb_eArgError);
     rb_eIconvIllegalSeq = rb_define_class_under(rb_cIconv, "IllegalSequence", rb_eArgError);
     rb_eIconvInvalidChar = rb_define_class_under(rb_cIconv, "InvalidCharacter", rb_eArgError);
     rb_eIconvOutOfRange = rb_define_class_under(rb_cIconv, "OutOfRange", rb_eRuntimeError);