diff --git a/ChangeLog b/ChangeLog
index 012f877fb0..7b367f9ff6 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,6 @@
+Fri Jul 29 16:12:02 005	 Keiju Ishitsuka <keiju@ruby-lang.org>
+	* lib/irb/context.rb: fix `irb --readline` option. [ruby-dev:40955]
+	
 Fri Jul 29 09:59:38 2005  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	* eval.c (rb_call0): fix calling zsuper from a method with anonymous
diff --git a/lib/irb/context.rb b/lib/irb/context.rb
index 043c12ade5..d01bd4aefa 100644
--- a/lib/irb/context.rb
+++ b/lib/irb/context.rb
@@ -58,12 +58,24 @@ module IRB
 
       case input_method
       when nil
-	if (defined?(ReadlineInputMethod) &&
-            (use_readline? || IRB.conf[:PROMPT_MODE] != :INF_RUBY && STDIN.tty?))
-	  @io = ReadlineInputMethod.new
-	else
+	case use_readline?
+	when nil
+	  if (defined?(ReadlineInputMethod) && STDIN.tty? &&
+	      IRB.conf[:PROMPT_MODE] != :INF_RUBY)
+	    @io = ReadlineInputMethod.new
+	  else
+	    @io = StdioInputMethod.new
+	  end
+	when false
 	  @io = StdioInputMethod.new
+	when true
+	  if defined?(ReadlineInputMethod)
+	    @io = ReadlineInputMethod.new
+	  else
+	    @io = StdioInputMethod.new
+	  end
 	end
+
       when String
 	@io = FileInputMethod.new(input_method)
 	@irb_name = File.basename(input_method)