diff --git a/lib/cgi/cookie.rb b/lib/cgi/cookie.rb
index 3ec884d..852e3ee 100644
--- a/lib/cgi/cookie.rb
+++ b/lib/cgi/cookie.rb
@@ -74,7 +74,7 @@ class CGI
       end
 
       options = name
-      unless options.has_key?("name")
+      unless options.key?("name")
         raise ArgumentError, "`name' required"
       end
 
@@ -150,7 +150,7 @@ class CGI
         name = CGI.unescape(name)
         values ||= ""
         values = values.split('&').collect{|v| CGI.unescape(v,@@accept_charset) }
-        if cookies.has_key?(name)
+        if cookies.key?(name)
           values = cookies[name].value + values
         end
         cookies[name] = Cookie.new(name, *values)
diff --git a/lib/cgi/core.rb b/lib/cgi/core.rb
index 08c2f77..731b08e 100644
--- a/lib/cgi/core.rb
+++ b/lib/cgi/core.rb
@@ -154,7 +154,7 @@ class CGI
       content_type = options
       buf = _header_for_string(content_type)
     elsif options.is_a?(Hash)
-      if options.size == 1 && options.has_key?('type')
+      if options.size == 1 && options.key?('type')
         content_type = options['type']
         buf = _header_for_string(content_type)
       else
@@ -717,7 +717,7 @@ class CGI
 
     # Returns true if a given query string parameter exists.
     def has_key?(*args)
-      @params.has_key?(*args)
+      @params.key?(*args)
     end
     alias key? has_key?
     alias include? has_key?
diff --git a/lib/cgi/html.rb b/lib/cgi/html.rb
index ed0c07b..7cbf3a0 100644
--- a/lib/cgi/html.rb
+++ b/lib/cgi/html.rb
@@ -311,10 +311,10 @@ class CGI
                      { "METHOD" => method, "ACTION" => action,
                        "ENCTYPE" => enctype }
                    else
-                     unless method.has_key?("METHOD")
+                     unless method.key?("METHOD")
                        method["METHOD"] = "post"
                      end
-                     unless method.has_key?("ENCTYPE")
+                     unless method.key?("ENCTYPE")
                        method["ENCTYPE"] = enctype
                      end
                      method
@@ -409,7 +409,7 @@ class CGI
       pretty = "  " if true == pretty
       buf = ""
 
-      if attributes.has_key?("DOCTYPE")
+      if attributes.key?("DOCTYPE")
         if attributes["DOCTYPE"]
           buf << attributes.delete("DOCTYPE")
         else
@@ -503,10 +503,10 @@ class CGI
                      { "METHOD" => "post", "ACTION" => action,
                        "ENCTYPE" => enctype }
                    else
-                     unless action.has_key?("METHOD")
+                     unless action.key?("METHOD")
                        action["METHOD"] = "post"
                      end
-                     unless action.has_key?("ENCTYPE")
+                     unless action.key?("ENCTYPE")
                        action["ENCTYPE"] = enctype
                      end
                      action
diff --git a/lib/drb/drb.rb b/lib/drb/drb.rb
index 26f39b7..91962b8 100644
--- a/lib/drb/drb.rb
+++ b/lib/drb/drb.rb
@@ -863,8 +863,8 @@ module DRb
                                   0,
                                   Socket::AI_PASSIVE)
       families = Hash[*infos.collect { |af, *_| af }.uniq.zip([]).flatten]
-      return TCPServer.open('0.0.0.0', port) if families.has_key?('AF_INET')
-      return TCPServer.open('::', port) if families.has_key?('AF_INET6')
+      return TCPServer.open('0.0.0.0', port) if families.key?('AF_INET')
+      return TCPServer.open('::', port) if families.key?('AF_INET6')
       return TCPServer.open(port)
       # :stopdoc:
     end
diff --git a/lib/mkmf.rb b/lib/mkmf.rb
index 6177e04..edb44a2 100644
--- a/lib/mkmf.rb
+++ b/lib/mkmf.rb
@@ -197,7 +197,7 @@ module MakeMakefile
         ['HDRDIR',        '$(rubyhdrdir)/ruby$(target_prefix)'],
         ['ARCHHDRDIR',    '$(rubyhdrdir)/$(arch)/ruby$(target_prefix)'],
       ]
-    elsif $configure_args.has_key?('--vendor')
+    elsif $configure_args.key?('--vendor')
       dirs = [
         ['BINDIR',        '$(bindir)'],
         ['RUBYCOMMONDIR', '$(vendordir)$(target_prefix)'],
@@ -1876,7 +1876,7 @@ VPATH = #{vpath.join(CONFIG['PATH_SEPARATOR'])}
       next unless /dir$/ =~ key
       mk << "#{key} = #{with_destdir(var)}\n"
     end
-    if !$extmk and !$configure_args.has_key?('--ruby') and
+    if !$extmk and !$configure_args.key?('--ruby') and
         sep = config_string('BUILD_FILE_SEPARATOR')
       sep = ":/=#{sep}"
     else
diff --git a/lib/net/imap.rb b/lib/net/imap.rb
index 85644f3..cbaa2e5 100644
--- a/lib/net/imap.rb
+++ b/lib/net/imap.rb
@@ -410,7 +410,7 @@ module Net
     # A Net::IMAP::NoResponseError is raised if authentication fails.
     def authenticate(auth_type, *args)
       auth_type = auth_type.upcase
-      unless @@authenticators.has_key?(auth_type)
+      unless @@authenticators.key?(auth_type)
         raise ArgumentError,
           format('unknown auth type - "%s"', auth_type)
       end
@@ -1195,7 +1195,7 @@ module Net
     end
 
     def record_response(name, data)
-      unless @responses.has_key?(name)
+      unless @responses.key?(name)
         @responses[name] = []
       end
       @responses[name].push(data)
@@ -3506,7 +3506,7 @@ module Net
       STAGE_TWO = :stage_two
 
       def nc(nonce)
-        if @nc.has_key? nonce
+        if @nc.key? nonce
           @nc[nonce] = @nc[nonce] + 1
         else
           @nc[nonce] = 1
diff --git a/lib/net/telnet.rb b/lib/net/telnet.rb
index f178a7b..c7130a5 100644
--- a/lib/net/telnet.rb
+++ b/lib/net/telnet.rb
@@ -272,12 +272,12 @@ module Net
     #
     def initialize(options) # :yield: mesg
       @options = options
-      @options["Host"]       = "localhost"   unless @options.has_key?("Host")
-      @options["Port"]       = 23            unless @options.has_key?("Port")
-      @options["Prompt"]     = /[$%#>] \z/n  unless @options.has_key?("Prompt")
-      @options["Timeout"]    = 10            unless @options.has_key?("Timeout")
-      @options["Waittime"]   = 0             unless @options.has_key?("Waittime")
-      unless @options.has_key?("Binmode")
+      @options["Host"]       = "localhost"   unless @options.key?("Host")
+      @options["Port"]       = 23            unless @options.key?("Port")
+      @options["Prompt"]     = /[$%#>] \z/n  unless @options.key?("Prompt")
+      @options["Timeout"]    = 10            unless @options.key?("Timeout")
+      @options["Waittime"]   = 0             unless @options.key?("Waittime")
+      unless @options.key?("Binmode")
         @options["Binmode"]    = false
       else
         unless (true == @options["Binmode"] or false == @options["Binmode"])
@@ -285,7 +285,7 @@ module Net
         end
       end
 
-      unless @options.has_key?("Telnetmode")
+      unless @options.key?("Telnetmode")
         @options["Telnetmode"] = true
       else
         unless (true == @options["Telnetmode"] or false == @options["Telnetmode"])
@@ -295,13 +295,13 @@ module Net
 
       @telnet_option = { "SGA" => false, "BINARY" => false }
 
-      if @options.has_key?("Output_log")
+      if @options.key?("Output_log")
         @log = File.open(@options["Output_log"], 'a+')
         @log.sync = true
         @log.binmode
       end
 
-      if @options.has_key?("Dump_log")
+      if @options.key?("Dump_log")
         @dumplog = File.open(@options["Dump_log"], 'a+')
         @dumplog.sync = true
         @dumplog.binmode
@@ -328,7 +328,7 @@ module Net
         end
       end
 
-      if @options.has_key?("Proxy")
+      if @options.key?("Proxy")
         if @options["Proxy"].kind_of?(Net::Telnet)
           @sock = @options["Proxy"].sock
         elsif @options["Proxy"].kind_of?(IO)
@@ -339,8 +339,8 @@ module Net
       else
         message = "Trying " + @options["Host"] + "...\n"
         yield(message) if block_given?
-        @log.write(message) if @options.has_key?("Output_log")
-        @dumplog.log_dump('#', message) if @options.has_key?("Dump_log")
+        @log.write(message) if @options.key?("Output_log")
+        @dumplog.log_dump('#', message) if @options.key?("Dump_log")
 
         begin
           if @options["Timeout"] == false
@@ -353,8 +353,8 @@ module Net
         rescue Net::OpenTimeout
           raise Net::OpenTimeout, "timed out while opening a connection to the host"
         rescue
-          @log.write($ERROR_INFO.to_s + "\n") if @options.has_key?("Output_log")
-          @dumplog.log_dump('#', $ERROR_INFO.to_s + "\n") if @options.has_key?("Dump_log")
+          @log.write($ERROR_INFO.to_s + "\n") if @options.key?("Output_log")
+          @dumplog.log_dump('#', $ERROR_INFO.to_s + "\n") if @options.key?("Dump_log")
           raise
         end
         @sock.sync = true
@@ -362,8 +362,8 @@ module Net
 
         message = "Connected to " + @options["Host"] + ".\n"
         yield(message) if block_given?
-        @log.write(message) if @options.has_key?("Output_log")
-        @dumplog.log_dump('#', message) if @options.has_key?("Dump_log")
+        @log.write(message) if @options.key?("Output_log")
+        @dumplog.log_dump('#', message) if @options.key?("Dump_log")
       end
 
     end # initialize
@@ -531,16 +531,16 @@ module Net
       fail_eof = @options["FailEOF"]
 
       if options.kind_of?(Hash)
-        prompt   = if options.has_key?("Match")
+        prompt   = if options.key?("Match")
                      options["Match"]
-                   elsif options.has_key?("Prompt")
+                   elsif options.key?("Prompt")
                      options["Prompt"]
-                   elsif options.has_key?("String")
+                   elsif options.key?("String")
                      Regexp.new( Regexp.quote(options["String"]) )
                    end
-        time_out = options["Timeout"]  if options.has_key?("Timeout")
-        waittime = options["Waittime"] if options.has_key?("Waittime")
-        fail_eof = options["FailEOF"]  if options.has_key?("FailEOF")
+        time_out = options["Timeout"]  if options.key?("Timeout")
+        waittime = options["Waittime"] if options.key?("Waittime")
+        fail_eof = options["FailEOF"]  if options.key?("FailEOF")
       else
         prompt = options
       end
@@ -558,7 +558,7 @@ module Net
         end
         begin
           c = @sock.readpartial(1024 * 1024)
-          @dumplog.log_dump('<', c) if @options.has_key?("Dump_log")
+          @dumplog.log_dump('<', c) if @options.key?("Dump_log")
           if @options["Telnetmode"]
             c = rest + c
             if Integer(c.rindex(/#{IAC}#{SE}/no) || 0) <
@@ -588,7 +588,7 @@ module Net
              buf.gsub!(/#{EOL}/no, "\n")
            end
           end
-          @log.print(buf) if @options.has_key?("Output_log")
+          @log.print(buf) if @options.key?("Output_log")
           line += buf
           yield buf if block_given?
         rescue EOFError # End of file reached
@@ -611,7 +611,7 @@ module Net
       length = string.length
       while 0 < length
         IO::select(nil, [@sock])
-        @dumplog.log_dump('>', string[-length..-1]) if @options.has_key?("Dump_log")
+        @dumplog.log_dump('>', string[-length..-1]) if @options.key?("Dump_log")
         length -= @sock.syswrite(string[-length..-1])
       end
     end
@@ -682,9 +682,9 @@ module Net
 
       if options.kind_of?(Hash)
         string   = options["String"]
-        match    = options["Match"]   if options.has_key?("Match")
-        time_out = options["Timeout"] if options.has_key?("Timeout")
-        fail_eof = options["FailEOF"] if options.has_key?("FailEOF")
+        match    = options["Match"]   if options.key?("Match")
+        time_out = options["Timeout"] if options.key?("Timeout")
+        fail_eof = options["FailEOF"] if options.key?("FailEOF")
       else
         string = options
       end
diff --git a/lib/rake/task_arguments.rb b/lib/rake/task_arguments.rb
index fc0d657..530278f 100644
--- a/lib/rake/task_arguments.rb
+++ b/lib/rake/task_arguments.rb
@@ -80,13 +80,13 @@ module Rake
 
     # Returns true if +key+ is one of the arguments
     def has_key?(key)
-      @hash.has_key?(key)
+      @hash.key?(key)
     end
 
     protected
 
     def lookup(name) # :nodoc:
-      if @hash.has_key?(name)
+      if @hash.key?(name)
         @hash[name]
       elsif @parent
         @parent.lookup(name)
diff --git a/lib/rexml/functions.rb b/lib/rexml/functions.rb
index 7809cc3..bd5bb70 100644
--- a/lib/rexml/functions.rb
+++ b/lib/rexml/functions.rb
@@ -252,7 +252,7 @@ module REXML
       map = {}
       0.upto(from.length - 1) { |pos|
         from_char = from[pos]
-        unless map.has_key? from_char
+        unless map.key? from_char
           map[from_char] =
           if pos < to.length
             to[pos]
@@ -264,11 +264,11 @@ module REXML
 
       if ''.respond_to? :chars
         string(string).chars.collect { |c|
-          if map.has_key? c then map[c] else c end
+          if map.key? c then map[c] else c end
         }.compact.join
       else
         string(string).unpack('U*').collect { |c|
-          if map.has_key? c then map[c] else c end
+          if map.key? c then map[c] else c end
         }.compact.pack('U*')
       end
     end
diff --git a/lib/rexml/parsers/baseparser.rb b/lib/rexml/parsers/baseparser.rb
index 4f0926f..01c04ce 100644
--- a/lib/rexml/parsers/baseparser.rb
+++ b/lib/rexml/parsers/baseparser.rb
@@ -398,7 +398,7 @@ module REXML
                     prefixes << prefix unless prefix == "xml"
                   end
 
-                  if attributes.has_key?(attr_name)
+                  if attributes.key?(attr_name)
                     msg = "Duplicate attribute #{attr_name.inspect}"
                     raise REXML::ParseException.new(msg, @source, self)
                   end
diff --git a/lib/rexml/parsers/sax2parser.rb b/lib/rexml/parsers/sax2parser.rb
index 40877ff..f8d2b56 100644
--- a/lib/rexml/parsers/sax2parser.rb
+++ b/lib/rexml/parsers/sax2parser.rb
@@ -161,7 +161,7 @@ module REXML
             copy = event[1].clone
 
             esub = proc { |match|
-              if @entities.has_key?($1)
+              if @entities.key?($1)
                 @entities[$1].gsub(Text::REFERENCE, &esub)
               else
                 match
diff --git a/lib/rss/atom.rb b/lib/rss/atom.rb
index 8133f72..cb1c73f 100644
--- a/lib/rss/atom.rb
+++ b/lib/rss/atom.rb
@@ -236,7 +236,7 @@ module RSS
           rel = link.rel || "alternate"
           next unless rel == "alternate"
           key = [link.hreflang, link.type]
-          if link_infos.has_key?(key)
+          if link_infos.key?(key)
             raise TooMuchTagError.new("link", tag_name)
           end
           link_infos[key] = true
diff --git a/lib/rss/parser.rb b/lib/rss/parser.rb
index 86e383c..38fbcf8 100644
--- a/lib/rss/parser.rb
+++ b/lib/rss/parser.rb
@@ -205,7 +205,7 @@ module RSS
 
       # test if this uri is registered against this name
       def uri_registered?(uri, name)
-        @@registered_uris[name].has_key?(uri)
+        @@registered_uris[name].key?(uri)
       end
 
       # record class_name for the supplied uri and tag_name
@@ -288,7 +288,7 @@ module RSS
     def instruction(name, content)
       if name == "xml-stylesheet"
         params = parse_pi_content(content)
-        if params.has_key?("href")
+        if params.key?("href")
           @xml_stylesheets << XMLStyleSheet.new(params)
         end
       end
diff --git a/lib/rss/rss.rb b/lib/rss/rss.rb
index 6c9b290..bac9852 100644
--- a/lib/rss/rss.rb
+++ b/lib/rss/rss.rb
@@ -846,7 +846,7 @@ EOC
       end
 
       def install_ns(prefix, uri)
-        if self::NSPOOL.has_key?(prefix)
+        if self::NSPOOL.key?(prefix)
           raise OverlappedPrefixError.new(prefix)
         end
         self::NSPOOL[prefix] = uri
@@ -951,7 +951,7 @@ EOC
       prefix = ""
       prefix << "#{klass.required_prefix}_" if klass.required_prefix
       key = "#{prefix}#{tag_name.gsub(/-/, '_')}"
-      if self.class.plural_forms.has_key?(key)
+      if self.class.plural_forms.key?(key)
         ary = __send__("#{self.class.plural_forms[key]}")
         ary << next_element
       else
@@ -1051,7 +1051,7 @@ EOC
         value = __send__(alias_name || name)
         return nil if required and value.nil?
         next if value.nil?
-        return nil if attrs.has_key?(name)
+        return nil if attrs.key?(name)
         attrs[name] = value
       end
       attrs
@@ -1223,7 +1223,7 @@ EOC
     def tag_filter(tags)
       rv = {}
       tags.each do |tag|
-        rv[tag[0]] = [] unless rv.has_key?(tag[0])
+        rv[tag[0]] = [] unless rv.key?(tag[0])
         rv[tag[0]].push(tag[1])
       end
       rv
diff --git a/lib/rubygems/commands/push_command.rb b/lib/rubygems/commands/push_command.rb
index 6899b48..b574324 100644
--- a/lib/rubygems/commands/push_command.rb
+++ b/lib/rubygems/commands/push_command.rb
@@ -78,7 +78,7 @@ You can upgrade or downgrade to the latest release version with:
     # Always include this, even if it's nil
     args << @host
 
-    if gem_data.spec.metadata.has_key?('allowed_push_host')
+    if gem_data.spec.metadata.key?('allowed_push_host')
       args << gem_data.spec.metadata['allowed_push_host']
     end
 
diff --git a/lib/webrick/cgi.rb b/lib/webrick/cgi.rb
index 80f636e..2181fe0 100644
--- a/lib/webrick/cgi.rb
+++ b/lib/webrick/cgi.rb
@@ -54,7 +54,7 @@ module WEBrick
 
     def initialize(*args)
       if defined?(MOD_RUBY)
-        unless ENV.has_key?("GATEWAY_INTERFACE")
+        unless ENV.key?("GATEWAY_INTERFACE")
           Apache.request.setup_cgi_env
         end
       end
diff --git a/lib/webrick/httpauth/digestauth.rb b/lib/webrick/httpauth/digestauth.rb
index 2a5e71e..b5b4094 100644
--- a/lib/webrick/httpauth/digestauth.rb
+++ b/lib/webrick/httpauth/digestauth.rb
@@ -172,7 +172,7 @@ module WEBrick
           req_params = MustParams
         end
         req_params.each{|key|
-          unless auth_req.has_key?(key)
+          unless auth_req.key?(key)
             error('%s: parameter missing. "%s"', auth_req['username'], key)
             raise HTTPStatus::BadRequest
           end
@@ -195,7 +195,7 @@ module WEBrick
           return false
         end
 
-        if (@qop.nil? && auth_req.has_key?('qop')) ||
+        if (@qop.nil? && auth_req.key?('qop')) ||
            (@qop && (! @qop.member?(auth_req['qop'])))
           error('%s: the qop is not allowed. "%s"',
                 auth_req['username'], auth_req['qop'])
diff --git a/lib/webrick/httpservlet/cgihandler.rb b/lib/webrick/httpservlet/cgihandler.rb
index 3210041..057d245 100644
--- a/lib/webrick/httpservlet/cgihandler.rb
+++ b/lib/webrick/httpservlet/cgihandler.rb
@@ -95,11 +95,11 @@ module WEBrick
             res.status = $1.to_i
             header.delete('status')
           end
-          if header.has_key?('location')
+          if header.key?('location')
             # RFC 3875 6.2.3, 6.2.4
             res.status = 302 unless (300...400) === res.status
           end
-          if header.has_key?('set-cookie')
+          if header.key?('set-cookie')
             header['set-cookie'].each{|k|
               res.cookies << Cookie.parse_set_cookie(k)
             }
diff --git a/lib/webrick/httputils.rb b/lib/webrick/httputils.rb
index 82f69f3..e7bf816 100644
--- a/lib/webrick/httputils.rb
+++ b/lib/webrick/httputils.rb
@@ -144,7 +144,7 @@ module WEBrick
         when /^([A-Za-z0-9!\#$%&'*+\-.^_`|~]+):\s*(.*?)\s*\z/om
           field, value = $1, $2
           field.downcase!
-          header[field] = [] unless header.has_key?(field)
+          header[field] = [] unless header.key?(field)
           header[field] << value
         when /^\s+(.*?)\s*\z/om
           value = $1
@@ -375,7 +375,7 @@ module WEBrick
           val = unescape_form(val.to_s)
           val = FormData.new(val)
           val.name = key
-          if query.has_key?(key)
+          if query.key?(key)
             query[key].append_data(val)
             next
           end
@@ -399,7 +399,7 @@ module WEBrick
           if data
             data.chop!
             key = data.name
-            if form_data.has_key?(key)
+            if form_data.key?(key)
               form_data[key].append_data(data)
             else
               form_data[key] = data
diff --git a/lib/xmlrpc/parser.rb b/lib/xmlrpc/parser.rb
index 791eb05..44b2f0f 100644
--- a/lib/xmlrpc/parser.rb
+++ b/lib/xmlrpc/parser.rb
@@ -177,7 +177,7 @@ module XMLRPC # :nodoc:
     # * <code>'faultString'</code> key is a String
     def self.fault(hash)
       if hash.kind_of? Hash and hash.size == 2 and
-        hash.has_key? "faultCode" and hash.has_key? "faultString" and
+        hash.key? "faultCode" and hash.key? "faultString" and
         hash["faultCode"].kind_of? Integer and hash["faultString"].kind_of? String
 
         XMLRPC::FaultException.new(hash["faultCode"], hash["faultString"])