diff --git a/ChangeLog b/ChangeLog
index ef1c6add20..bcb655b8e6 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Wed Apr 25 05:46:12 2012  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* lib/optparse.rb (OptionParser#to_a): split for each lines.
+	  [ruby-dev:45568][Bug #6348]
+
 Tue Apr 24 21:57:53 2012  Tanaka Akira  <akr@fsij.org>
 
 	* ext/socket/raddrinfo.c (init_unix_addrinfo): show actual path length
diff --git a/lib/optparse.rb b/lib/optparse.rb
index da022c9450..dcb67604e2 100644
--- a/lib/optparse.rb
+++ b/lib/optparse.rb
@@ -1071,7 +1071,7 @@ XXX
   #
   # Returns option summary list.
   #
-  def to_a; summarize("#{banner}".split) end
+  def to_a; summarize("#{banner}".split(/^/)) end
 
   #
   # Checks if an argument is given twice, in which case an ArgumentError is
diff --git a/test/optparse/test_summary.rb b/test/optparse/test_summary.rb
index 2fad5f04dc..d7771733a3 100644
--- a/test/optparse/test_summary.rb
+++ b/test/optparse/test_summary.rb
@@ -33,6 +33,6 @@ class TestOptionParser::SummaryTest < TestOptionParser
   def test_summary
     o = OptionParser.new("foo\nbar")
     assert_equal("foo\nbar\n", o.to_s)
-    assert_equal(["foo", "bar"], o.to_a)
+    assert_equal(["foo\n", "bar"], o.to_a)
   end
 end