diff --git a/ChangeLog b/ChangeLog
index 7d29ef79b7..19f0748c9a 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,4 +1,4 @@
-Thu Nov  6 10:17:51 2003  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+Thu Nov  6 11:01:19 2003  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	* ext/stringio/stringio.c (strio_set_string, strio_reopen): check
 	  tainted.
@@ -11,6 +11,9 @@ Thu Nov  6 10:17:51 2003  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 	* ruby.c (proc_options): reserve searched script path in the
 	  source file name table.  [ruby-list:38765]
 
+	* lib/optparse.rb (OptionParser::Completion#complete): default not to
+	  ignore case on completion.  [ruby-talk:84726]
+
 Wed Nov  5 23:49:45 2003  NAKAMURA, Hiroshi  <nahi@ruby-lang.org>
 
 	* sample/openssl/gen_csr.rb: there (at least) is a CA which does not
diff --git a/lib/optparse.rb b/lib/optparse.rb
index f0b97ba12e..96609b219d 100644
--- a/lib/optparse.rb
+++ b/lib/optparse.rb
@@ -80,7 +80,8 @@ Keyword completion module.
         completion pattern.
 =end #'#"#`#
     def complete(key, pat = nil)
-      pat ||= Regexp.new('\A' + Regexp.quote(key).gsub(/\w+(?=.)/, '\&\w*'), true)
+      pat ||= Regexp.new('\A' + Regexp.quote(key).gsub(/\w+(?=.)/, '\&\w*'),
+                         ignore_case?)
       canon, sw, k, v = nil
       each do |k, *v|
 	(if Regexp === k
@@ -109,6 +110,10 @@ Keyword completion module.
     def convert(opt = nil, val = nil, *)
       val
     end
+
+    def ignore_case?
+      false
+    end
   end
 
 =begin private
@@ -122,6 +127,11 @@ Map from option/keyword string to object with completion.
   class OptionMap < Hash
     include Completion
   end
+  class OptionCaseMap < OptionMap
+    def ignore_case?
+      true
+    end
+  end
 
 
 =begin
@@ -383,7 +393,7 @@ summary feature.
     def initialize
       @atype = {}
       @short = OptionMap.new
-      @long = OptionMap.new
+      @long = OptionCaseMap.new
       @list = []
     end