diff --git a/ChangeLog b/ChangeLog
index 7baa8af1cb..bfc950d8c0 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,17 @@
+Fri Apr  3 14:02:42 2009  Akinori MUSHA  <knu@iDaemons.org>
+
+	* lib/irb/completion.rb (IRB::InputCompletor::Operators): Add
+	  overloadable negative operators.
+
+	* lib/irb/ruby-lex.rb (RubyLex#lex_init): Support overloadable
+	  negative operators.
+
+	* lib/irb/ruby-lex.rb (RubyLex#identify_identifier): Minus signs
+	  need to be escaped in regexp character class.
+
+	* misc/ruby-mode.el (ruby-font-lock-keywords, ruby-parse-partial):
+	  Support overloadable negative operators.
+
 Wed Apr  1 20:37:49 2009  Tanaka Akira  <akr@fsij.org>
 
 	* configure.in (rb_cv_fork_with_pthread): fail if the child process
diff --git a/lib/irb/completion.rb b/lib/irb/completion.rb
index 26339f217d..8278d8ff87 100644
--- a/lib/irb/completion.rb
+++ b/lib/irb/completion.rb
@@ -184,7 +184,7 @@ module IRB
 
     Operators = ["%", "&", "*", "**", "+",  "-",  "/",
       "<", "<<", "<=", "<=>", "==", "===", "=~", ">", ">=", ">>",
-      "[]", "[]=", "^",]
+      "[]", "[]=", "^", "!", "!=", "!~"]
 
     def self.select_message(receiver, message, candidates)
       candidates.grep(/^#{message}/).collect do |e|
diff --git a/lib/irb/ruby-lex.rb b/lib/irb/ruby-lex.rb
index b21f0d34f8..93dc229f31 100644
--- a/lib/irb/ruby-lex.rb
+++ b/lib/irb/ruby-lex.rb
@@ -389,7 +389,8 @@ class RubyLex
 		  "=", "==", "===", 
 		  "=~", "<=>",	
 		  "<", "<=",
-		  ">", ">=", ">>") do
+		  ">", ">=", ">>",
+		  "!", "!=", "!~") do
       |op, io|
       case @lex_state
       when EXPR_FNAME, EXPR_DOT
@@ -400,12 +401,6 @@ class RubyLex
       Token(op)
     end
 
-    @OP.def_rules("!", "!=", "!~") do
-      |op, io|
-      @lex_state = EXPR_BEG
-      Token(op)
-    end
-
     @OP.def_rules("<<") do
       |op, io|
       tk = nil
@@ -822,11 +817,11 @@ class RubyLex
 	      when "class"
 		valid = false unless peek_match?(/^\s*(<<|\w|::)/)
 	      when "def"
-		valid = false if peek_match?(/^\s*(([+-\/*&\|^]|<<|>>|\|\||\&\&)=|\&\&|\|\|)/)
+		valid = false if peek_match?(/^\s*(([+\-\/*&\|^]|<<|>>|\|\||\&\&)=|\&\&|\|\|)/)
 	      when "do"
-		valid = false if peek_match?(/^\s*([+-\/*]?=|\*|<|>|\&)/)
+		valid = false if peek_match?(/^\s*([+\-\/*]?=|\*|<|>|\&)/)
 	      when *ENINDENT_CLAUSE
-		valid = false if peek_match?(/^\s*([+-\/*]?=|\*|<|>|\&|\|)/)
+		valid = false if peek_match?(/^\s*([+\-\/*]?=|\*|<|>|\&|\|)/)
 	      else
 		# no nothing
 	      end
diff --git a/misc/ruby-mode.el b/misc/ruby-mode.el
index 0b8ed825fa..70acd7266b 100644
--- a/misc/ruby-mode.el
+++ b/misc/ruby-mode.el
@@ -646,7 +646,7 @@ The variable ruby-indent-level controls the amount of indentation.
        ((looking-at ":\\(['\"]\\)")
         (goto-char (match-beginning 1))
         (ruby-forward-string (buffer-substring (match-beginning 1) (match-end 1)) end))
-       ((looking-at ":\\([-,.+*/%&|^~<>]=?\\|===?\\|<=>\\)")
+       ((looking-at ":\\([-,.+*/%&|^~<>]=?\\|===?\\|<=>\\|![~=]?\\)")
         (goto-char (match-end 0)))
        ((looking-at ":\\([a-zA-Z_][a-zA-Z_0-9]*[!?=]?\\)?")
         (goto-char (match-end 0)))
@@ -1386,7 +1386,7 @@ buffer position `limit' or the end of the buffer."
      '("\\(^\\|[^_]\\)\\b\\([A-Z]+\\(\\w\\|_\\)*\\)"
        2 font-lock-type-face)
      ;; symbols
-     '("\\(^\\|[^:]\\)\\(:\\([-+~]@?\\|[/%&|^`]\\|\\*\\*?\\|<\\(<\\|=>?\\)?\\|>[>=]?\\|===?\\|=~\\|\\[\\]=?\\|\\(\\w\\|_\\)+\\([!?=]\\|\\b_*\\)\\|#{[^}\n\\\\]*\\(\\\\.[^}\n\\\\]*\\)*}\\)\\)"
+     '("\\(^\\|[^:]\\)\\(:\\([-+~]@?\\|[/%&|^`]\\|\\*\\*?\\|<\\(<\\|=>?\\)?\\|>[>=]?\\|===?\\|=~\\|![~=]?\\|\\[\\]=?\\|\\(\\w\\|_\\)+\\([!?=]\\|\\b_*\\)\\|#{[^}\n\\\\]*\\(\\\\.[^}\n\\\\]*\\)*}\\)\\)"
        2 font-lock-reference-face)
      ;; expression expansion
      '("#\\({[^}\n\\\\]*\\(\\\\.[^}\n\\\\]*\\)*}\\|\\(\\$\\|@\\|@@\\)\\(\\w\\|_\\)+\\)"