diff --git a/lib/set.rb b/lib/set.rb
index f00cfac..a3f1855 100644
--- a/lib/set.rb
+++ b/lib/set.rb
@@ -78,7 +78,7 @@ def self.[](*ary)
   # If a block is given, the elements of enum are preprocessed by the
   # given block.
   def initialize(enum = nil, &block) # :yields: o
-    @hash ||= Hash.new
+    @hash ||= Hash.new(false)
 
     enum.nil? and return
 
@@ -209,7 +209,7 @@ def flatten!
 
   # Returns true if the set contains the given object.
   def include?(o)
-    @hash.include?(o)
+    @hash[o]
   end
   alias member? include?