diff -r 09105051b9f4 Lib/test/test_textwrap.py
--- a/Lib/test/test_textwrap.py	Sun Nov 03 21:31:38 2013 +0200
+++ b/Lib/test/test_textwrap.py	Wed Nov 06 19:47:24 2013 +0000
@@ -732,6 +732,14 @@
         expect = "hello there\n  how are you?"
         self.assertEqual(expect, dedent(text))
 
+    def test_dedent_works_with_lf_and_crlf(self):
+        lf = '  a\n  b\n\n  c'
+        expect = 'a\nb\n\nc'
+        self.assertEqual(expect, dedent(lf))
+
+        crlf = lf.replace('\n', '\r\n')
+        expect = expect.replace('\n', '\r\n')
+        self.assertEqual(expect, dedent(crlf))
 
 # Test textwrap.indent
 class IndentTestCase(unittest.TestCase):
diff -r 09105051b9f4 Lib/textwrap.py
--- a/Lib/textwrap.py	Sun Nov 03 21:31:38 2013 +0200
+++ b/Lib/textwrap.py	Wed Nov 06 19:47:24 2013 +0000
@@ -395,7 +395,8 @@
 # -- Loosely related functionality -------------------------------------
 
 _whitespace_only_re = re.compile('^[ \t]+$', re.MULTILINE)
-_leading_whitespace_re = re.compile('(^[ \t]*)(?:[^ \t\n])', re.MULTILINE)
+_leading_whitespace_re = re.compile('(^[ \t]*)[^\r\n]', re.MULTILINE)
+
 
 def dedent(text):
     """Remove any common leading whitespace from every line in `text`.