diff --git a/README.md b/README.md
index 8c379f5..4d842dd 100644
--- a/README.md
+++ b/README.md
@@ -85,6 +85,9 @@ u'''foo'''  # '''foo'''
 # `ur` is not a valid string prefix in python3
 u'\d'   # u'\\d'
 
+# this fixes a syntax error in python3.3+
+'\N'    # r'\N'
+
 # note: pyupgrade is timid in one case (that's usually a mistake)
 # in python2.x `'\u2603'` is the same as `'\\u2603'` without `unicode_literals`
 # but in python3.x, that's our friend ☃
diff --git a/pyupgrade.py b/pyupgrade.py
index 2a55816..f1d25ec 100644
--- a/pyupgrade.py
+++ b/pyupgrade.py
@@ -456,11 +456,9 @@ ESCAPE_STARTS = frozenset((
     '\n', '\r', '\\', "'", '"', 'a', 'b', 'f', 'n', 'r', 't', 'v',
     '0', '1', '2', '3', '4', '5', '6', '7',  # octal escapes
     'x',  # hex escapes
-    # only valid in non-bytestrings
-    'N', 'u', 'U',
 ))
-ESCAPE_STARTS_BYTES = ESCAPE_STARTS - frozenset(('N', 'u', 'U'))
 ESCAPE_RE = re.compile(r'\\.', re.DOTALL)
+NAMED_ESCAPE_NAME = re.compile(r'\{[^}]+\}')
 
 
 def _parse_string_literal(s):
@@ -475,18 +473,31 @@ def _fix_escape_sequences(token):
     if 'r' in actual_prefix or '\\' not in rest:
         return token
 
-    if 'b' in actual_prefix:
-        valid_escapes = ESCAPE_STARTS_BYTES
-    else:
-        valid_escapes = ESCAPE_STARTS
+    is_bytestring = 'b' in actual_prefix
+
+    def _is_valid_escape(match):
+        c = match.group()[1]
+        return (
+            c in ESCAPE_STARTS or
+            (not is_bytestring and c in 'uU') or
+            (
+                not is_bytestring and
+                c == 'N' and
+                bool(NAMED_ESCAPE_NAME.match(rest, match.end()))
+            )
+        )
 
-    escape_sequences = {m[1] for m in ESCAPE_RE.findall(rest)}
-    has_valid_escapes = escape_sequences & valid_escapes
-    has_invalid_escapes = escape_sequences - valid_escapes
+    has_valid_escapes = False
+    has_invalid_escapes = False
+    for match in ESCAPE_RE.finditer(rest):
+        if _is_valid_escape(match):
+            has_valid_escapes = True
+        else:
+            has_invalid_escapes = True
 
     def cb(match):
         matched = match.group()
-        if matched[1] in valid_escapes:
+        if _is_valid_escape(match):
             return matched
         else:
             return r'\{}'.format(matched)

diff --git a/tests/pyupgrade_test.py b/tests/pyupgrade_test.py
index fa8edc4..a3f75cb 100644
--- a/tests/pyupgrade_test.py
+++ b/tests/pyupgrade_test.py
@@ -432,6 +432,8 @@ def test_fix_ur_literals_gets_fixed_before_u_removed():
         '"\\u2603"',
         # don't touch already valid escapes
         r'"\r\n"',
+        # python3.3+ named unicode escapes
+        r'"\N{SNOWMAN}"',
         # don't touch escaped newlines
         '"""\\\n"""', '"""\\\r\n"""', '"""\\\r"""',
     ),
@@ -459,6 +461,10 @@ def test_fix_escape_sequences_noop(s):
         ('"""\\\n\\q"""', '"""\\\n\\\\q"""'),
         ('"""\\\r\n\\q"""', '"""\\\r\n\\\\q"""'),
         ('"""\\\r\\q"""', '"""\\\r\\\\q"""'),
+        # python2.x allows \N, in python3.3+ this is a syntax error
+        (r'"\N"', r'r"\N"'), (r'"\N\n"', r'"\\N\n"'),
+        (r'"\N{SNOWMAN}\q"', r'"\N{SNOWMAN}\\q"'),
+        (r'b"\N{SNOWMAN}"', r'br"\N{SNOWMAN}"'),
     ),
 )
 def test_fix_escape_sequences(s, expected):

py2-py3 invalid escape sequence: '\N' should get rewritten
This is a syntax error in python3.x:

```python
'\N'
```
tests/pyupgrade_test.py::test_fix_escape_sequences["\\N"-r"\\N"] tests/pyupgrade_test.py::test_fix_escape_sequences["\\N\\n"-"\\\\N\\n"]
tests/pyupgrade_test.py::test_roundtrip_text[] tests/pyupgrade_test.py::test_roundtrip_text[foo] tests/pyupgrade_test.py::test_roundtrip_text[{}] tests/pyupgrade_test.py::test_roundtrip_text[{0}] tests/pyupgrade_test.py::test_roundtrip_text[{named}] tests/pyupgrade_test.py::test_roundtrip_text[{!r}] tests/pyupgrade_test.py::test_roundtrip_text[{:>5}] tests/pyupgrade_test.py::test_roundtrip_text[{{] tests/pyupgrade_test.py::test_roundtrip_text[}}] tests/pyupgrade_test.py::test_roundtrip_text[{0!s:15}] tests/pyupgrade_test.py::test_intentionally_not_round_trip[{:}-{}] tests/pyupgrade_test.py::test_intentionally_not_round_trip[{0:}-{0}] tests/pyupgrade_test.py::test_intentionally_not_round_trip[{0!r:}-{0!r}] tests/pyupgrade_test.py::test_sets[set()-set()] tests/pyupgrade_test.py::test_sets[set((\n))-set((\n))] tests/pyupgrade_test.py::test_sets[set tests/pyupgrade_test.py::test_sets[set(())-set()] tests/pyupgrade_test.py::test_sets[set([])-set()] tests/pyupgrade_test.py::test_sets[set(( tests/pyupgrade_test.py::test_sets[set((1, tests/pyupgrade_test.py::test_sets[set([1, tests/pyupgrade_test.py::test_sets[set(x tests/pyupgrade_test.py::test_sets[set([x tests/pyupgrade_test.py::test_sets[set((x tests/pyupgrade_test.py::test_sets[set(((1, tests/pyupgrade_test.py::test_sets[set((a, tests/pyupgrade_test.py::test_sets[set([(1, tests/pyupgrade_test.py::test_sets[set(\n tests/pyupgrade_test.py::test_sets[set([((1, tests/pyupgrade_test.py::test_sets[set((((1, tests/pyupgrade_test.py::test_sets[set(\n(1, tests/pyupgrade_test.py::test_sets[set((\n1,\n2,\n))\n-{\n1,\n2,\n}\n] tests/pyupgrade_test.py::test_sets[set((frozenset(set((1, tests/pyupgrade_test.py::test_sets[set((1,))-{1}] tests/pyupgrade_test.py::test_dictcomps[x tests/pyupgrade_test.py::test_dictcomps[dict()-dict()] tests/pyupgrade_test.py::test_dictcomps[(-(] tests/pyupgrade_test.py::test_dictcomps[dict tests/pyupgrade_test.py::test_dictcomps[dict((a, tests/pyupgrade_test.py::test_dictcomps[dict([a, tests/pyupgrade_test.py::test_dictcomps[dict(((a, tests/pyupgrade_test.py::test_dictcomps[dict([(a, tests/pyupgrade_test.py::test_dictcomps[dict(((a), tests/pyupgrade_test.py::test_dictcomps[dict((k, tests/pyupgrade_test.py::test_dictcomps[dict(\n tests/pyupgrade_test.py::test_dictcomps[x(\n tests/pyupgrade_test.py::test_fix_is_compare_to_literal_noop[x tests/pyupgrade_test.py::test_fix_is_compare_to_literal[`is`] tests/pyupgrade_test.py::test_fix_is_compare_to_literal[`is tests/pyupgrade_test.py::test_fix_is_compare_to_literal[string] tests/pyupgrade_test.py::test_fix_is_compare_to_literal[unicode tests/pyupgrade_test.py::test_fix_is_compare_to_literal[bytes] tests/pyupgrade_test.py::test_fix_is_compare_to_literal[float] tests/pyupgrade_test.py::test_fix_is_compare_to_literal[compound tests/pyupgrade_test.py::test_fix_is_compare_to_literal[multi-line tests/pyupgrade_test.py::test_format_literals["{0}"format(1)-"{0}"format(1)] tests/pyupgrade_test.py::test_format_literals['{}'.format(1)-'{}'.format(1)] tests/pyupgrade_test.py::test_format_literals['{'.format(1)-'{'.format(1)] tests/pyupgrade_test.py::test_format_literals['}'.format(1)-'}'.format(1)] tests/pyupgrade_test.py::test_format_literals[x tests/pyupgrade_test.py::test_format_literals['{0} tests/pyupgrade_test.py::test_format_literals['{0}'.format(1)-'{}'.format(1)] tests/pyupgrade_test.py::test_format_literals['{0:x}'.format(30)-'{:x}'.format(30)] tests/pyupgrade_test.py::test_format_literals['''{0}\n{1}\n'''.format(1, tests/pyupgrade_test.py::test_format_literals['{0}' tests/pyupgrade_test.py::test_format_literals[print(\n tests/pyupgrade_test.py::test_format_literals['{0:<{1}}'.format(1, tests/pyupgrade_test.py::test_imports_unicode_literals[import tests/pyupgrade_test.py::test_imports_unicode_literals[from tests/pyupgrade_test.py::test_imports_unicode_literals[x tests/pyupgrade_test.py::test_imports_unicode_literals["""docstring"""\nfrom tests/pyupgrade_test.py::test_unicode_literals[(-False-(] tests/pyupgrade_test.py::test_unicode_literals[u''-False-u''] tests/pyupgrade_test.py::test_unicode_literals[u''-True-''] tests/pyupgrade_test.py::test_unicode_literals[from tests/pyupgrade_test.py::test_unicode_literals["""with tests/pyupgrade_test.py::test_unicode_literals[Regression: tests/pyupgrade_test.py::test_fix_ur_literals[basic tests/pyupgrade_test.py::test_fix_ur_literals[upper tests/pyupgrade_test.py::test_fix_ur_literals[with tests/pyupgrade_test.py::test_fix_ur_literals[emoji] tests/pyupgrade_test.py::test_fix_ur_literals_gets_fixed_before_u_removed tests/pyupgrade_test.py::test_fix_escape_sequences_noop[""] tests/pyupgrade_test.py::test_fix_escape_sequences_noop[r"\\d"] tests/pyupgrade_test.py::test_fix_escape_sequences_noop[r'\\d'] tests/pyupgrade_test.py::test_fix_escape_sequences_noop[r"""\\d"""] tests/pyupgrade_test.py::test_fix_escape_sequences_noop[r'''\\d'''] tests/pyupgrade_test.py::test_fix_escape_sequences_noop[rb"\\d"] tests/pyupgrade_test.py::test_fix_escape_sequences_noop["\\\\d"] tests/pyupgrade_test.py::test_fix_escape_sequences_noop["\\u2603"] tests/pyupgrade_test.py::test_fix_escape_sequences_noop["\\r\\n"] tests/pyupgrade_test.py::test_fix_escape_sequences_noop["\\N{SNOWMAN}"] tests/pyupgrade_test.py::test_fix_escape_sequences_noop["""\\\n"""] tests/pyupgrade_test.py::test_fix_escape_sequences_noop["""\\\r\n"""] tests/pyupgrade_test.py::test_fix_escape_sequences_noop["""\\\r"""] tests/pyupgrade_test.py::test_fix_escape_sequences["\\d"-r"\\d"] tests/pyupgrade_test.py::test_fix_escape_sequences["\\n\\d"-"\\n\\\\d"] tests/pyupgrade_test.py::test_fix_escape_sequences[u"\\d"-u"\\\\d"] tests/pyupgrade_test.py::test_fix_escape_sequences[b"\\d"-br"\\d"] tests/pyupgrade_test.py::test_fix_escape_sequences["\\8"-r"\\8"] tests/pyupgrade_test.py::test_fix_escape_sequences["\\9"-r"\\9"] tests/pyupgrade_test.py::test_fix_escape_sequences[b"\\u2603"-br"\\u2603"] tests/pyupgrade_test.py::test_fix_escape_sequences["""\\\n\\q"""-"""\\\n\\\\q"""] tests/pyupgrade_test.py::test_fix_escape_sequences["""\\\r\n\\q"""-"""\\\r\n\\\\q"""] tests/pyupgrade_test.py::test_fix_escape_sequences["""\\\r\\q"""-"""\\\r\\\\q"""] tests/pyupgrade_test.py::test_fix_escape_sequences["\\N{SNOWMAN}\\q"-"\\N{SNOWMAN}\\\\q"] tests/pyupgrade_test.py::test_fix_escape_sequences[b"\\N{SNOWMAN}"-br"\\N{SNOWMAN}"] tests/pyupgrade_test.py::test_noop_octal_literals[0] tests/pyupgrade_test.py::test_noop_octal_literals[00] tests/pyupgrade_test.py::test_noop_octal_literals[1] tests/pyupgrade_test.py::test_noop_octal_literals[12345] tests/pyupgrade_test.py::test_noop_octal_literals[1.2345] tests/pyupgrade_test.py::test_fix_extra_parens_noop[print("hello tests/pyupgrade_test.py::test_fix_extra_parens_noop[print((1, tests/pyupgrade_test.py::test_fix_extra_parens_noop[print(())] tests/pyupgrade_test.py::test_fix_extra_parens_noop[print((\n))] tests/pyupgrade_test.py::test_fix_extra_parens_noop[sum((block.code tests/pyupgrade_test.py::test_fix_extra_parens_noop[def tests/pyupgrade_test.py::test_fix_extra_parens[print(("hello tests/pyupgrade_test.py::test_fix_extra_parens[print(("foo{}".format(1)))-print("foo{}".format(1))] tests/pyupgrade_test.py::test_fix_extra_parens[print((((1))))-print(1)] tests/pyupgrade_test.py::test_fix_extra_parens[print(\n tests/pyupgrade_test.py::test_fix_extra_parens[extra tests/pyupgrade_test.py::test_is_bytestring_true[b''] tests/pyupgrade_test.py::test_is_bytestring_true[b""] tests/pyupgrade_test.py::test_is_bytestring_true[B""] tests/pyupgrade_test.py::test_is_bytestring_true[B''] tests/pyupgrade_test.py::test_is_bytestring_true[rb''0] tests/pyupgrade_test.py::test_is_bytestring_true[rb''1] tests/pyupgrade_test.py::test_is_bytestring_false[] tests/pyupgrade_test.py::test_is_bytestring_false[""] tests/pyupgrade_test.py::test_is_bytestring_false[''] tests/pyupgrade_test.py::test_is_bytestring_false[u""] tests/pyupgrade_test.py::test_is_bytestring_false["b"] tests/pyupgrade_test.py::test_parse_percent_format[""-expected0] tests/pyupgrade_test.py::test_parse_percent_format["%%"-expected1] tests/pyupgrade_test.py::test_parse_percent_format["%s"-expected2] tests/pyupgrade_test.py::test_parse_percent_format["%s tests/pyupgrade_test.py::test_parse_percent_format["%(hi)s"-expected4] tests/pyupgrade_test.py::test_parse_percent_format["%()s"-expected5] tests/pyupgrade_test.py::test_parse_percent_format["%#o"-expected6] tests/pyupgrade_test.py::test_parse_percent_format["% tests/pyupgrade_test.py::test_parse_percent_format["%5d"-expected8] tests/pyupgrade_test.py::test_parse_percent_format["%*d"-expected9] tests/pyupgrade_test.py::test_parse_percent_format["%.f"-expected10] tests/pyupgrade_test.py::test_parse_percent_format["%.5f"-expected11] tests/pyupgrade_test.py::test_parse_percent_format["%.*f"-expected12] tests/pyupgrade_test.py::test_parse_percent_format["%ld"-expected13] tests/pyupgrade_test.py::test_parse_percent_format["%(complete)#4.4f"-expected14] tests/pyupgrade_test.py::test_percent_to_format[%s-{}] tests/pyupgrade_test.py::test_percent_to_format[%%%s-%{}] tests/pyupgrade_test.py::test_percent_to_format[%(foo)s-{foo}] tests/pyupgrade_test.py::test_percent_to_format[%2f-{:2f}] tests/pyupgrade_test.py::test_percent_to_format[%r-{!r}] tests/pyupgrade_test.py::test_percent_to_format[%a-{!a}] tests/pyupgrade_test.py::test_simplify_conversion_flag[-] tests/pyupgrade_test.py::test_simplify_conversion_flag[ tests/pyupgrade_test.py::test_simplify_conversion_flag[#0- tests/pyupgrade_test.py::test_simplify_conversion_flag[--<] tests/pyupgrade_test.py::test_percent_format_noop["%s" tests/pyupgrade_test.py::test_percent_format_noop[b"%s" tests/pyupgrade_test.py::test_percent_format_noop["%*s" tests/pyupgrade_test.py::test_percent_format_noop["%.*s" tests/pyupgrade_test.py::test_percent_format_noop["%d" tests/pyupgrade_test.py::test_percent_format_noop["%i" tests/pyupgrade_test.py::test_percent_format_noop["%u" tests/pyupgrade_test.py::test_percent_format_noop["%c" tests/pyupgrade_test.py::test_percent_format_noop["%#o" tests/pyupgrade_test.py::test_percent_format_noop["%()s" tests/pyupgrade_test.py::test_percent_format_noop["%4%" tests/pyupgrade_test.py::test_percent_format_noop["%.2r" tests/pyupgrade_test.py::test_percent_format_noop["%.2a" tests/pyupgrade_test.py::test_percent_format_noop[i tests/pyupgrade_test.py::test_percent_format_noop["%(1)s" tests/pyupgrade_test.py::test_percent_format_noop["%(a)s" tests/pyupgrade_test.py::test_percent_format_noop["%(ab)s" tests/pyupgrade_test.py::test_percent_format_noop["%(and)s" tests/pyupgrade_test.py::test_percent_format["trivial" tests/pyupgrade_test.py::test_percent_format["%s" tests/pyupgrade_test.py::test_percent_format["%s%% tests/pyupgrade_test.py::test_percent_format["%3f" tests/pyupgrade_test.py::test_percent_format["%-5s" tests/pyupgrade_test.py::test_percent_format["%9s" tests/pyupgrade_test.py::test_percent_format["brace tests/pyupgrade_test.py::test_percent_format["%(k)s" tests/pyupgrade_test.py::test_percent_format["%(to_list)s" tests/pyupgrade_test.py::test_fix_super_noop[x(] tests/pyupgrade_test.py::test_fix_super_noop[class tests/pyupgrade_test.py::test_fix_super_noop[def tests/pyupgrade_test.py::test_fix_super[class tests/pyupgrade_test.py::test_fix_classes_noop[x tests/pyupgrade_test.py::test_fix_classes_noop[class tests/pyupgrade_test.py::test_fix_classes[class tests/pyupgrade_test.py::test_fix_classes[import tests/pyupgrade_test.py::test_fix_classes[from tests/pyupgrade_test.py::test_fix_six_noop[x tests/pyupgrade_test.py::test_fix_six_noop[@ tests/pyupgrade_test.py::test_fix_six_noop[from tests/pyupgrade_test.py::test_fix_six_noop[@mydec\nclass tests/pyupgrade_test.py::test_fix_six_noop[print(six.raise_from(exc, tests/pyupgrade_test.py::test_fix_six_noop[print(six.b("\xa3"))] tests/pyupgrade_test.py::test_fix_six_noop[print(six.b( tests/pyupgrade_test.py::test_fix_six_noop[class tests/pyupgrade_test.py::test_fix_six[isinstance(s, tests/pyupgrade_test.py::test_fix_six[weird tests/pyupgrade_test.py::test_fix_six[issubclass(tp, tests/pyupgrade_test.py::test_fix_six[STRING_TYPES tests/pyupgrade_test.py::test_fix_six[from tests/pyupgrade_test.py::test_fix_six[six.b("123")-b"123"] tests/pyupgrade_test.py::test_fix_six[six.b(r"123")-br"123"] tests/pyupgrade_test.py::test_fix_six[six.b("\\x12\\xef")-b"\\x12\\xef"] tests/pyupgrade_test.py::test_fix_six[@six.python_2_unicode_compatible\nclass tests/pyupgrade_test.py::test_fix_six[@six.python_2_unicode_compatible\n@other_decorator\nclass tests/pyupgrade_test.py::test_fix_six[six.get_unbound_method(meth)\n-meth\n] tests/pyupgrade_test.py::test_fix_six[six.indexbytes(bs, tests/pyupgrade_test.py::test_fix_six[six.assertCountEqual(\n tests/pyupgrade_test.py::test_fix_six[six.raise_from(exc, tests/pyupgrade_test.py::test_fix_six[six.reraise(tp, tests/pyupgrade_test.py::test_fix_six[six.reraise(\n tests/pyupgrade_test.py::test_fix_six[class tests/pyupgrade_test.py::test_fix_classes_py3only[class tests/pyupgrade_test.py::test_fix_classes_py3only[from tests/pyupgrade_test.py::test_fix_fstrings_noop[(] tests/pyupgrade_test.py::test_fix_fstrings_noop["{}" tests/pyupgrade_test.py::test_fix_fstrings_noop["{}".format(\n tests/pyupgrade_test.py::test_fix_fstrings_noop["{} tests/pyupgrade_test.py::test_fix_fstrings_noop["{foo} tests/pyupgrade_test.py::test_fix_fstrings_noop["{0} tests/pyupgrade_test.py::test_fix_fstrings_noop["{x} tests/pyupgrade_test.py::test_fix_fstrings_noop["{x.y} tests/pyupgrade_test.py::test_fix_fstrings_noop[b"{} tests/pyupgrade_test.py::test_fix_fstrings_noop["{:{}}".format(x, tests/pyupgrade_test.py::test_fix_fstrings_noop["{a[b]}".format(a=a)] tests/pyupgrade_test.py::test_fix_fstrings_noop["{a.a[b]}".format(a=a)] tests/pyupgrade_test.py::test_fix_fstrings["{} tests/pyupgrade_test.py::test_fix_fstrings["{1} tests/pyupgrade_test.py::test_fix_fstrings["{x.y}".format(x=z)-f"{z.y}"] tests/pyupgrade_test.py::test_fix_fstrings["{.x} tests/pyupgrade_test.py::test_fix_fstrings["hello tests/pyupgrade_test.py::test_fix_fstrings["{}{{}}{}".format(escaped, tests/pyupgrade_test.py::test_main_trivial tests/pyupgrade_test.py::test_main_noop tests/pyupgrade_test.py::test_main_changes_a_file tests/pyupgrade_test.py::test_main_keeps_line_endings tests/pyupgrade_test.py::test_main_syntax_error tests/pyupgrade_test.py::test_main_non_utf8_bytes tests/pyupgrade_test.py::test_keep_percent_format tests/pyupgrade_test.py::test_py3_plus_argument_unicode_literals tests/pyupgrade_test.py::test_py3_plus_super tests/pyupgrade_test.py::test_py3_plus_new_style_classes tests/pyupgrade_test.py::test_py36_plus_fstrings