diff --git a/lib/date.rb b/lib/date.rb
index 66fa67a..070cf7f 100644
--- a/lib/date.rb
+++ b/lib/date.rb
@@ -1478,11 +1478,9 @@ class Date
   # we reach +limit+ (inclusive), yielding the resultant
   # date at each step.
   def step(limit, step=1) # :yield: date
-=begin
     if step.zero?
       raise ArgumentError, "step can't be 0"
     end
-=end
     unless block_given?
       return to_enum(:step, limit, step)
     end
diff --git a/test/date/test_date_arith.rb b/test/date/test_date_arith.rb
index 745ddbd..00e1bac 100644
--- a/test/date/test_date_arith.rb
+++ b/test/date/test_date_arith.rb
@@ -261,6 +261,14 @@ class TestDateArith < Test::Unit::TestCase
     assert_equal(8, e.to_a.size)
   end
 
+  def test_step__0
+    p = Date.new(2001,1,14)
+    q = Date.new(2001,1,21)
+    assert_raises(ArgumentError) do
+      p.step(q, 0){|d|}
+    end
+  end
+
 =begin
   def test_step__inf
     p = Date.new(2001,1,14)