diff --git a/lib/drb/drb.rb b/lib/drb/drb.rb
index 25cf7e9..26f39b7 100644
--- a/lib/drb/drb.rb
+++ b/lib/drb/drb.rb
@@ -995,7 +995,7 @@ module DRb
     def initialize(option)
       @option = option.to_s
     end
-    attr :option
+    attr_reader :option
     def to_s; @option; end
 
     def ==(other)
diff --git a/lib/irb/ruby-token.rb b/lib/irb/ruby-token.rb
index 52aebe7..a80d81c 100644
--- a/lib/irb/ruby-token.rb
+++ b/lib/irb/ruby-token.rb
@@ -24,14 +24,14 @@ module RubyToken
       @line_no = line_no
       @char_no = char_no
     end
-    attr :seek, :line_no, :char_no
+    attr_reader :seek, :line_no, :char_no
   end
 
   class TkNode < Token
     def initialize(seek, line_no, char_no)
       super
     end
-    attr :node
+    attr_reader :node
   end
 
   class TkId < Token
@@ -39,7 +39,7 @@ module RubyToken
       super(seek, line_no, char_no)
       @name = name
     end
-    attr :name
+    attr_reader :name
   end
 
   class TkVal < Token
@@ -47,7 +47,7 @@ module RubyToken
       super(seek, line_no, char_no)
       @value = value
     end
-    attr :value
+    attr_reader :value
   end
 
   class TkOp < Token
@@ -60,7 +60,7 @@ module RubyToken
       op = TkReading2Token[op][0] unless op.kind_of?(Symbol)
       @op = op
     end
-    attr :op
+    attr_reader :op
   end
 
   class TkUnknownChar < Token
@@ -68,7 +68,7 @@ module RubyToken
       super(seek, line_no, char_no)
       @name = name
     end
-    attr :name
+    attr_reader :name
   end
 
   class TkError < Token
diff --git a/lib/net/telnet.rb b/lib/net/telnet.rb
index 3c5d6e8..2260e7f 100644
--- a/lib/net/telnet.rb
+++ b/lib/net/telnet.rb
@@ -371,7 +371,7 @@ module Net
     # The socket the Telnet object is using.  Note that this object becomes
     # a delegate of the Telnet object, so normally you invoke its methods
     # directly on the Telnet object.
-    attr :sock
+    attr_reader :sock
 
     # Set telnet command interpretation on (+mode+ == true) or off
     # (+mode+ == false), or return the current value (+mode+ not
diff --git a/lib/rdoc/ruby_token.rb b/lib/rdoc/ruby_token.rb
index 8010475..81d3eb0 100644
--- a/lib/rdoc/ruby_token.rb
+++ b/lib/rdoc/ruby_token.rb
@@ -38,9 +38,9 @@ module RDoc::RubyToken
       @text = text
     end
 
-    attr :seek
-    attr :line_no
-    attr :char_no
+    attr_reader :seek
+    attr_reader :line_no
+    attr_reader :char_no
 
     attr_accessor :text
 
@@ -73,7 +73,7 @@ module RDoc::RubyToken
       @node = node
     end
 
-    attr :node
+    attr_reader :node
 
     def ==(other)
       self.class == other.class and
@@ -101,7 +101,7 @@ module RDoc::RubyToken
       super(seek, line_no, char_no)
       @name = name
     end
-    attr :name
+    attr_reader :name
 
     def ==(other)
       self.class == other.class and
@@ -192,7 +192,7 @@ module RDoc::RubyToken
       @text = nil
     end
 
-    attr :op
+    attr_reader :op
 
     def ==(other)
       self.class == other.class and
@@ -217,7 +217,7 @@ module RDoc::RubyToken
       super(seek, line_no, char_no)
       @name = name
     end
-    attr :name
+    attr_reader :name
 
     def ==(other)
       self.class == other.class and
diff --git a/lib/thwait.rb b/lib/thwait.rb
index 60f3911..d9750a4 100644
--- a/lib/thwait.rb
+++ b/lib/thwait.rb
@@ -55,7 +55,7 @@ class ThreadsWait
   end
 
   # Returns the array of threads that have not terminated yet.
-  attr :threads
+  attr_reader :threads
 
   #
   # Returns +true+ if there are no threads in the pool still running.