diff --git a/lib/date.rb b/lib/date.rb
index 37c7630..70e2b00 100644
--- a/lib/date.rb
+++ b/lib/date.rb
@@ -1002,15 +1002,26 @@ class Date
 
   class << self
 
-    def once(*ids) # :nodoc:
-      for id in ids
-	module_eval <<-"end;"
-	  alias_method :__#{id.to_i}__, :#{id.to_s}
-	  private :__#{id.to_i}__
-	  def #{id.to_s}(*args, &block)
-	    (@__#{id.to_i}__ ||= [__#{id.to_i}__(*args, &block)])[0]
-	  end
-	end;
+    def once(*meths)
+      meths.each do |meth|
+        # Alias
+        orig_meth = '__nonmemoized_' + meth.to_s
+        alias_method orig_meth, meth
+
+        # Redefine
+        define_method(meth) do |*args|
+          # Get cache
+          @__memoization_cache ||= {}
+          @__memoization_cache[meth] ||= {}
+
+          # Recalculate or fetch
+          cache = @__memoization_cache[meth]
+          if !cache.has_key?(args)
+            cache[args] = send(orig_meth, *args)
+          else
+            result = cache[args]
+          end
+        end
       end
     end
 
@@ -1037,7 +1048,10 @@ class Date
   #
   # Using one of the factory methods such as Date::civil is
   # generally easier and safer.
-  def initialize(ajd=0, of=0, sg=ITALY) @ajd, @of, @sg = ajd, of, sg end
+  def initialize(ajd=0, of=0, sg=ITALY)
+    @ajd, @of, @sg = ajd, of, sg
+    @__memoization_cache = {}
+  end
 
   # Get the date as an Astronomical Julian Day Number.
   def ajd() @ajd end
diff --git a/test/ruby/test_date.rb b/test/ruby/test_date.rb
new file mode 100644
index 0000000..45cb184
--- /dev/null
+++ b/test/ruby/test_date.rb
@@ -0,0 +1,13 @@
+require 'test/unit'
+
+require 'date'
+
+class TestDate < Test::Unit::TestCase
+
+  def test_freeze
+    foo = Date.new
+    foo.freeze
+    foo.year
+  end
+
+end