diff -r d14eac872a46 Lib/difflib.py
--- a/Lib/difflib.py	Tue Apr 05 02:29:30 2011 +0200
+++ b/Lib/difflib.py	Tue Apr 05 15:50:32 2011 +0800
@@ -1194,7 +1194,8 @@
             yield '+++ %s%s%s' % (tofile, todate, lineterm)
             started = True
         i1, i2, j1, j2 = group[0][1], group[-1][2], group[0][3], group[-1][4]
-        yield "@@ -%d,%d +%d,%d @@%s" % (i1+1, i2-i1, j1+1, j2-j1, lineterm)
+        yield "@@ -%d,%d +%d,%d @@%s" % (i1 + 1 if (i1, i2) != (0, 0) else 0,
+                i2-i1, j1+1, j2-j1, lineterm)
         for tag, i1, i2, j1, j2 in group:
             if tag == 'equal':
                 for line in a[i1:i2]:
diff -r d14eac872a46 Lib/test/test_difflib.py
--- a/Lib/test/test_difflib.py	Tue Apr 05 02:29:30 2011 +0200
+++ b/Lib/test/test_difflib.py	Tue Apr 05 15:50:32 2011 +0800
@@ -236,6 +236,11 @@
         cd = difflib.context_diff(*args, lineterm='')
         self.assertEqual(list(cd)[0:2], ["*** Original", "--- Current"])
 
+    def test_one_file_empty(self):
+        ud = difflib.unified_diff([], ['a\n', 'b\n'])
+        self.assertEqual(list(ud), ['--- \n', '+++ \n', '@@ -0,0 +1,2 @@\n',
+            '+a\n', '+b\n'])
+
 
 def test_main():
     difflib.HtmlDiff._default_prefix = 0