diff --git a/Tests/check_icns_dos.py b/Tests/check_icns_dos.py
index e56709bbb..d4c3cf7cb 100644
--- a/Tests/check_icns_dos.py
+++ b/Tests/check_icns_dos.py
@@ -2,10 +2,11 @@
 # Run from anywhere that PIL is importable.
 
 from PIL import Image
+from PIL._util import py3
 from io import BytesIO
 
-if bytes is str:
-    Image.open(BytesIO(bytes('icns\x00\x00\x00\x10hang\x00\x00\x00\x00')))
-else:
+if py3:
     Image.open(BytesIO(bytes('icns\x00\x00\x00\x10hang\x00\x00\x00\x00',
                              'latin-1')))
+else:
+    Image.open(BytesIO(bytes('icns\x00\x00\x00\x10hang\x00\x00\x00\x00')))
diff --git a/Tests/check_j2k_dos.py b/Tests/check_j2k_dos.py
index 9f06888a3..4ea31cec2 100644
--- a/Tests/check_j2k_dos.py
+++ b/Tests/check_j2k_dos.py
@@ -2,12 +2,14 @@
 # Run from anywhere that PIL is importable.
 
 from PIL import Image
+from PIL._util import py3
 from io import BytesIO
 
-if bytes is str:
-    Image.open(BytesIO(bytes(
-        '\x00\x00\x00\x0cjP\x20\x20\x0d\x0a\x87\x0a\x00\x00\x00\x00hang')))
-else:
+if py3:
     Image.open(BytesIO(bytes(
         '\x00\x00\x00\x0cjP\x20\x20\x0d\x0a\x87\x0a\x00\x00\x00\x00hang',
         'latin-1')))
+
+else:
+    Image.open(BytesIO(bytes(
+        '\x00\x00\x00\x0cjP\x20\x20\x0d\x0a\x87\x0a\x00\x00\x00\x00hang')))
diff --git a/Tests/helper.py b/Tests/helper.py
index 606dca006..d70b6f51d 100644
--- a/Tests/helper.py
+++ b/Tests/helper.py
@@ -8,6 +8,7 @@ import os
 import unittest
 
 from PIL import Image, ImageMath
+from PIL._util import py3
 
 import logging
 logger = logging.getLogger(__name__)
@@ -265,8 +266,6 @@ class PillowLeakTestCase(PillowTestCase):
 
 # helpers
 
-py3 = sys.version_info.major >= 3
-
 if not py3:
     # Remove DeprecationWarning in Python 3
     PillowTestCase.assertRaisesRegex = PillowTestCase.assertRaisesRegexp
diff --git a/Tests/test_file_eps.py b/Tests/test_file_eps.py
index bd7c79f82..9d6bed060 100644
--- a/Tests/test_file_eps.py
+++ b/Tests/test_file_eps.py
@@ -1,6 +1,7 @@
 from helper import unittest, PillowTestCase, hopper
 
 from PIL import Image, EpsImagePlugin
+from PIL._util import py3
 import io
 
 # Our two EPS test files (they are identical except for their bounding boxes)
@@ -206,19 +207,19 @@ class TestFileEps(PillowTestCase):
         self._test_readline(t, ending)
 
     def _test_readline_io(self, test_string, ending):
-        if str is bytes:
-            t = io.StringIO(unicode(test_string))
-        else:
+        if py3:
             t = io.StringIO(test_string)
+        else:
+            t = io.StringIO(unicode(test_string))
         self._test_readline(t, ending)
 
     def _test_readline_file_universal(self, test_string, ending):
         f = self.tempfile('temp.txt')
         with open(f, 'wb') as w:
-            if str is bytes:
-                w.write(test_string)
-            else:
+            if py3:
                 w.write(test_string.encode('UTF-8'))
+            else:
+                w.write(test_string)
 
         with open(f, 'rU') as t:
             self._test_readline(t, ending)
@@ -226,10 +227,10 @@ class TestFileEps(PillowTestCase):
     def _test_readline_file_psfile(self, test_string, ending):
         f = self.tempfile('temp.txt')
         with open(f, 'wb') as w:
-            if str is bytes:
-                w.write(test_string)
-            else:
+            if py3:
                 w.write(test_string.encode('UTF-8'))
+            else:
+                w.write(test_string)
 
         with open(f, 'rb') as r:
             t = EpsImagePlugin.PSFile(r)
diff --git a/Tests/test_file_libtiff.py b/Tests/test_file_libtiff.py
index dc3b10845..05433d9b6 100644
--- a/Tests/test_file_libtiff.py
+++ b/Tests/test_file_libtiff.py
@@ -1,6 +1,7 @@
 from __future__ import print_function
-from helper import unittest, PillowTestCase, hopper, py3
+from helper import unittest, PillowTestCase, hopper
 from PIL import features
+from PIL._util import py3
 
 from ctypes import c_float
 import io
diff --git a/Tests/test_file_png.py b/Tests/test_file_png.py
index abf3f2953..c78351464 100644
--- a/Tests/test_file_png.py
+++ b/Tests/test_file_png.py
@@ -1,5 +1,6 @@
 from helper import unittest, PillowTestCase, PillowLeakTestCase, hopper
 from PIL import Image, ImageFile, PngImagePlugin
+from PIL._util import py3
 
 from io import BytesIO
 import zlib
@@ -419,7 +420,7 @@ class TestFilePng(PillowTestCase):
             im = roundtrip(im, pnginfo=info)
             self.assertEqual(im.info, {"Text": value})
 
-        if str is not bytes:
+        if py3:
             rt_text(" Aa" + chr(0xa0) + chr(0xc4) + chr(0xff))  # Latin1
             rt_text(chr(0x400) + chr(0x472) + chr(0x4ff))       # Cyrillic
             rt_text(chr(0x4e00) + chr(0x66f0) +                 # CJK
diff --git a/Tests/test_file_tiff.py b/Tests/test_file_tiff.py
index 334f5c96b..282a0c676 100644
--- a/Tests/test_file_tiff.py
+++ b/Tests/test_file_tiff.py
@@ -3,9 +3,10 @@ from io import BytesIO
 import struct
 import sys
 
-from helper import unittest, PillowTestCase, hopper, py3
+from helper import unittest, PillowTestCase, hopper
 
 from PIL import Image, TiffImagePlugin
+from PIL._util import py3
 from PIL.TiffImagePlugin import X_RESOLUTION, Y_RESOLUTION, RESOLUTION_UNIT
 
 logger = logging.getLogger(__name__)
diff --git a/Tests/test_font_pcf.py b/Tests/test_font_pcf.py
index 0b757b963..20869505f 100644
--- a/Tests/test_font_pcf.py
+++ b/Tests/test_font_pcf.py
@@ -2,6 +2,7 @@ from helper import unittest, PillowTestCase
 
 from PIL import Image, FontFile, PcfFontFile
 from PIL import ImageFont, ImageDraw
+from PIL._util import py3
 
 codecs = dir(Image.core)
 
@@ -76,7 +77,7 @@ class TestFontPcf(PillowTestCase):
         message = "".join(chr(i+1) for i in range(140, 232))
         self._test_high_characters(message)
         # accept bytes instances in Py3.
-        if bytes is not str:
+        if py3:
             self._test_high_characters(message.encode('latin1'))
 
 
diff --git a/Tests/test_format_hsv.py b/Tests/test_format_hsv.py
index 2cc54c910..31309da60 100644
--- a/Tests/test_format_hsv.py
+++ b/Tests/test_format_hsv.py
@@ -1,6 +1,7 @@
 from helper import unittest, PillowTestCase, hopper
 
 from PIL import Image
+from PIL._util import py3
 
 import colorsys
 import itertools
@@ -57,10 +58,10 @@ class TestFormatHSV(PillowTestCase):
 
         (r, g, b) = im.split()
 
-        if bytes is str:
-            conv_func = self.str_to_float
-        else:
+        if py3:
             conv_func = self.int_to_float
+        else:
+            conv_func = self.str_to_float
 
         if hasattr(itertools, 'izip'):
             iter_helper = itertools.izip
@@ -72,11 +73,11 @@ class TestFormatHSV(PillowTestCase):
                      for (_r, _g, _b) in iter_helper(r.tobytes(), g.tobytes(),
                                                      b.tobytes())]
 
-        if str is bytes:
-            new_bytes = b''.join(chr(h)+chr(s)+chr(v) for (
+        if py3:
+            new_bytes = b''.join(bytes(chr(h)+chr(s)+chr(v), 'latin-1') for (
                 h, s, v) in converted)
         else:
-            new_bytes = b''.join(bytes(chr(h)+chr(s)+chr(v), 'latin-1') for (
+            new_bytes = b''.join(chr(h)+chr(s)+chr(v) for (
                 h, s, v) in converted)
 
         hsv = Image.frombytes(mode, r.size, new_bytes)
diff --git a/Tests/test_image.py b/Tests/test_image.py
index f64ea241b..7222e389b 100644
--- a/Tests/test_image.py
+++ b/Tests/test_image.py
@@ -1,6 +1,7 @@
 from helper import unittest, PillowTestCase, hopper
 
 from PIL import Image
+from PIL._util import py3
 import os
 
 
@@ -60,12 +61,12 @@ class TestImage(PillowTestCase):
         self.assertEqual(im.height, 4)
 
     def test_invalid_image(self):
-        if str is bytes:
-            import StringIO
-            im = StringIO.StringIO('')
-        else:
+        if py3:
             import io
             im = io.BytesIO(b'')
+        else:
+            import StringIO
+            im = StringIO.StringIO('')
         self.assertRaises(IOError, Image.open, im)
 
     def test_bad_mode(self):
diff --git a/Tests/test_image_getim.py b/Tests/test_image_getim.py
index bc562de5a..1452e584e 100644
--- a/Tests/test_image_getim.py
+++ b/Tests/test_image_getim.py
@@ -1,4 +1,5 @@
-from helper import unittest, PillowTestCase, hopper, py3
+from helper import unittest, PillowTestCase, hopper
+from PIL._util import py3
 
 
 class TestImageGetIm(PillowTestCase):
diff --git a/Tests/test_imagepath.py b/Tests/test_imagepath.py
index 98a6d3416..8df71121d 100644
--- a/Tests/test_imagepath.py
+++ b/Tests/test_imagepath.py
@@ -1,6 +1,7 @@
 from helper import unittest, PillowTestCase
 
 from PIL import ImagePath, Image
+from PIL._util import py3
 
 import array
 import struct
@@ -77,10 +78,10 @@ class TestImagePath(PillowTestCase):
             # This fails due to the invalid malloc above,
             # and segfaults
             for i in range(200000):
-                if str is bytes:
-                    x[i] = "0"*16
-                else:
+                if py3:
                     x[i] = b'0'*16
+                else:
+                    x[i] = "0"*16
 
 
 class evil:
diff --git a/Tests/test_imagetk.py b/Tests/test_imagetk.py
index dd0d67d5e..2df35c584 100644
--- a/Tests/test_imagetk.py
+++ b/Tests/test_imagetk.py
@@ -1,5 +1,6 @@
-from helper import unittest, PillowTestCase, hopper, py3
+from helper import unittest, PillowTestCase, hopper
 from PIL import Image
+from PIL._util import py3
 
 
 try:
diff --git a/src/PIL/EpsImagePlugin.py b/src/PIL/EpsImagePlugin.py
index b50348771..1ae7865b1 100644
--- a/src/PIL/EpsImagePlugin.py
+++ b/src/PIL/EpsImagePlugin.py
@@ -26,6 +26,7 @@ import os
 import sys
 from . import Image, ImageFile
 from ._binary import i32le as i32
+from ._util import py3
 
 __version__ = "0.5"
 
@@ -206,12 +207,12 @@ class EpsImageFile(ImageFile.ImageFile):
         # Rewrap the open file pointer in something that will
         # convert line endings and decode to latin-1.
         try:
-            if bytes is str:
-                # Python2, no encoding conversion necessary
-                fp = open(self.fp.name, "Ur")
-            else:
+            if py3:
                 # Python3, can use bare open command.
                 fp = open(self.fp.name, "Ur", encoding='latin-1')
+            else:
+                # Python2, no encoding conversion necessary
+                fp = open(self.fp.name, "Ur")
         except:
             # Expect this for bytesio/stringio
             fp = PSFile(self.fp)
diff --git a/src/PIL/Image.py b/src/PIL/Image.py
index 9057c5f8d..bf187f2d4 100644
--- a/src/PIL/Image.py
+++ b/src/PIL/Image.py
@@ -25,6 +25,7 @@
 #
 
 from . import VERSION, PILLOW_VERSION, _plugins
+from ._util import py3
 
 import logging
 import warnings
@@ -1260,10 +1261,10 @@ class Image(object):
 
         self.load()
         try:
-            if bytes is str:
-                return [i8(c) for c in self.im.getpalette()]
-            else:
+            if py3:
                 return list(self.im.getpalette())
+            else:
+                return [i8(c) for c in self.im.getpalette()]
         except ValueError:
             return None  # no palette
 
@@ -1586,10 +1587,10 @@ class Image(object):
             palette = ImagePalette.raw(data.rawmode, data.palette)
         else:
             if not isinstance(data, bytes):
-                if bytes is str:
-                    data = "".join(chr(x) for x in data)
-                else:
+                if py3:
                     data = bytes(data)
+                else:
+                    data = "".join(chr(x) for x in data)
             palette = ImagePalette.raw(rawmode, data)
         self.mode = "P"
         self.palette = palette
diff --git a/src/PIL/ImageFont.py b/src/PIL/ImageFont.py
index f3b55e0c4..5ae6c3a4e 100644
--- a/src/PIL/ImageFont.py
+++ b/src/PIL/ImageFont.py
@@ -26,7 +26,7 @@
 #
 
 from . import Image
-from ._util import isDirectory, isPath
+from ._util import isDirectory, isPath, py3
 import os
 import sys
 
@@ -314,10 +314,10 @@ def load_path(filename):
     for directory in sys.path:
         if isDirectory(directory):
             if not isinstance(filename, str):
-                if bytes is str:
-                    filename = filename.encode("utf-8")
-                else:
+                if py3:
                     filename = filename.decode("utf-8")
+                else:
+                    filename = filename.encode("utf-8")
             try:
                 return load(os.path.join(directory, filename))
             except IOError:
diff --git a/src/PIL/ImageMath.py b/src/PIL/ImageMath.py
index c5bea708a..d985877a6 100644
--- a/src/PIL/ImageMath.py
+++ b/src/PIL/ImageMath.py
@@ -16,6 +16,7 @@
 #
 
 from . import Image, _imagingmath
+from ._util import py3
 
 try:
     import builtins
@@ -100,7 +101,7 @@ class _Operand(object):
         # an image is "true" if it contains at least one non-zero pixel
         return self.im.getbbox() is not None
 
-    if bytes is str:
+    if not py3:
         # Provide __nonzero__ for pre-Py3k
         __nonzero__ = __bool__
         del __bool__
@@ -151,7 +152,7 @@ class _Operand(object):
     def __rpow__(self, other):
         return self.apply("pow", other, self)
 
-    if bytes is str:
+    if not py3:
         # Provide __div__ and __rdiv__ for pre-Py3k
         __div__ = __truediv__
         __rdiv__ = __rtruediv__
diff --git a/src/PIL/ImageQt.py b/src/PIL/ImageQt.py
index 280cbc6fc..ca5fff180 100644
--- a/src/PIL/ImageQt.py
+++ b/src/PIL/ImageQt.py
@@ -17,7 +17,7 @@
 #
 
 from . import Image
-from ._util import isPath
+from ._util import isPath, py3
 from io import BytesIO
 
 qt_is_installed = True
@@ -123,10 +123,10 @@ def _toqclass_helper(im):
     # handle filename, if given instead of image name
     if hasattr(im, "toUtf8"):
         # FIXME - is this really the best way to do this?
-        if str is bytes:
-            im = unicode(im.toUtf8(), "utf-8")
-        else:
+        if py3:
             im = str(im.toUtf8(), "utf-8")
+        else:
+            im = unicode(im.toUtf8(), "utf-8")
     if isPath(im):
         im = Image.open(im)
 
diff --git a/src/PIL/PSDraw.py b/src/PIL/PSDraw.py
index de34713ea..1c17c61b2 100644
--- a/src/PIL/PSDraw.py
+++ b/src/PIL/PSDraw.py
@@ -16,6 +16,7 @@
 #
 
 from . import EpsImagePlugin
+from ._util import py3
 import sys
 
 ##
@@ -34,7 +35,7 @@ class PSDraw(object):
         self.fp = fp
 
     def _fp_write(self, to_write):
-        if bytes is str or self.fp == sys.stdout:
+        if not py3 or self.fp == sys.stdout:
             self.fp.write(to_write)
         else:
             self.fp.write(bytes(to_write, 'UTF-8'))
diff --git a/src/PIL/PdfParser.py b/src/PIL/PdfParser.py
index 5cc5a1bbb..ceea7dd2e 100644
--- a/src/PIL/PdfParser.py
+++ b/src/PIL/PdfParser.py
@@ -4,6 +4,7 @@ import mmap
 import os
 import re
 import zlib
+from ._util import py3
 
 try:
     from UserDict import UserDict  # Python 2.x
@@ -11,12 +12,12 @@ except ImportError:
     UserDict = collections.UserDict  # Python 3.x
 
 
-if str == bytes:  # Python 2.x
-    def make_bytes(s):  # pragma: no cover
-        return s        # pragma: no cover
-else:  # Python 3.x
+if py3:  # Python 3.x
     def make_bytes(s):
         return s.encode("us-ascii")
+else:  # Python 2.x
+    def make_bytes(s):  # pragma: no cover
+        return s        # pragma: no cover
 
 
 # see 7.9.2.2 Text String Type on page 86 and D.3 PDFDocEncoding Character Set on page 656
@@ -72,10 +73,10 @@ PDFDocEncoding = {
 def decode_text(b):
     if b[:len(codecs.BOM_UTF16_BE)] == codecs.BOM_UTF16_BE:
         return b[len(codecs.BOM_UTF16_BE):].decode("utf_16_be")
-    elif str == bytes:  # Python 2.x
-        return u"".join(PDFDocEncoding.get(ord(byte), byte) for byte in b)
-    else:
+    elif py3:  # Python 3.x
         return "".join(PDFDocEncoding.get(byte, chr(byte)) for byte in b)
+    else:  # Python 2.x
+        return u"".join(PDFDocEncoding.get(ord(byte), byte) for byte in b)
 
 
 class PdfFormatError(RuntimeError):
@@ -214,20 +215,18 @@ class PdfName:
     allowed_chars = set(range(33, 127)) - set(ord(c) for c in "#%/()<>[]{}")
 
     def __bytes__(self):
-        if str == bytes:  # Python 2.x
-            result = bytearray(b"/")
-            for b in self.name:
-                if ord(b) in self.allowed_chars:
-                    result.append(b)
-                else:
-                    result.extend(b"#%02X" % ord(b))
-        else:  # Python 3.x
-            result = bytearray(b"/")
-            for b in self.name:
+        result = bytearray(b"/")
+        for b in self.name:
+            if py3:  # Python 3.x
                 if b in self.allowed_chars:
                     result.append(b)
                 else:
                     result.extend(make_bytes("#%02X" % b))
+            else:  # Python 2.x
+                if ord(b) in self.allowed_chars:
+                    result.append(b)
+                else:
+                    result.extend(b"#%02X" % ord(b))
         return bytes(result)
 
     __str__ = __bytes__
@@ -281,7 +280,7 @@ class PdfDict(UserDict):
         out.extend(b"\n>>")
         return bytes(out)
 
-    if str == bytes:
+    if not py3:
         __str__ = __bytes__
 
 
@@ -289,13 +288,13 @@ class PdfBinary:
     def __init__(self, data):
         self.data = data
 
-    if str == bytes:  # Python 2.x
+    if py3:  # Python 3.x
+        def __bytes__(self):
+            return make_bytes("<%s>" % "".join("%02X" % b for b in self.data))
+    else:  # Python 2.x
         def __str__(self):
             return "<%s>" % "".join("%02X" % ord(b) for b in self.data)
 
-    else:  # Python 3.x
-        def __bytes__(self):
-            return make_bytes("<%s>" % "".join("%02X" % b for b in self.data))
 
 
 class PdfStream:
@@ -333,7 +332,7 @@ def pdf_repr(x):
         return bytes(PdfDict(x))
     elif isinstance(x, list):
         return bytes(PdfArray(x))
-    elif (str == bytes and isinstance(x, unicode)) or (str != bytes and isinstance(x, str)):
+    elif (py3 and isinstance(x, str)) or (not py3 and isinstance(x, unicode)):
         return pdf_repr(encode_text(x))
     elif isinstance(x, bytes):
         return b"(" + x.replace(b"\\", b"\\\\").replace(b"(", b"\\(").replace(b")", b"\\)") + b")"  # XXX escape more chars? handle binary garbage
diff --git a/src/PIL/PngImagePlugin.py b/src/PIL/PngImagePlugin.py
index 9eb364206..826061990 100644
--- a/src/PIL/PngImagePlugin.py
+++ b/src/PIL/PngImagePlugin.py
@@ -38,6 +38,7 @@ import struct
 
 from . import Image, ImageFile, ImagePalette
 from ._binary import i8, i16be as i16, i32be as i32, o16be as o16, o32be as o32
+from ._util import py3
 
 __version__ = "0.9"
 
@@ -437,7 +438,7 @@ class PngStream(ChunkStream):
             k = s
             v = b""
         if k:
-            if bytes is not str:
+            if py3:
                 k = k.decode('latin-1', 'strict')
                 v = v.decode('latin-1', 'replace')
 
@@ -473,7 +474,7 @@ class PngStream(ChunkStream):
             v = b""
 
         if k:
-            if bytes is not str:
+            if py3:
                 k = k.decode('latin-1', 'strict')
                 v = v.decode('latin-1', 'replace')
 
@@ -510,7 +511,7 @@ class PngStream(ChunkStream):
                     return s
             else:
                 return s
-        if bytes is not str:
+        if py3:
             try:
                 k = k.decode("latin-1", "strict")
                 lang = lang.decode("utf-8", "strict")
diff --git a/src/PIL/SgiImagePlugin.py b/src/PIL/SgiImagePlugin.py
index 8b34561e5..ef0f40ebd 100644
--- a/src/PIL/SgiImagePlugin.py
+++ b/src/PIL/SgiImagePlugin.py
@@ -24,6 +24,7 @@
 
 from . import Image, ImageFile
 from ._binary import i8, o8, i16be as i16
+from ._util import py3
 import struct
 import os
 
@@ -165,7 +166,7 @@ def _save(im, fp, filename):
     pinmax = 255
     # Image name (79 characters max, truncated below in write)
     imgName = os.path.splitext(os.path.basename(filename))[0]
-    if str is not bytes:
+    if py3:
         imgName = imgName.encode('ascii', 'ignore')
     # Standard representation of pixel in the file
     colormap = 0
diff --git a/src/PIL/TiffImagePlugin.py b/src/PIL/TiffImagePlugin.py
index f9039183e..167f0cba1 100644
--- a/src/PIL/TiffImagePlugin.py
+++ b/src/PIL/TiffImagePlugin.py
@@ -43,6 +43,7 @@ from __future__ import division, print_function
 
 from . import Image, ImageFile, ImagePalette, TiffTags
 from ._binary import i8, o8
+from ._util import py3
 
 import collections
 from fractions import Fraction
@@ -519,7 +520,7 @@ class ImageFileDirectory_v2(collections.MutableMapping):
     def __contains__(self, tag):
         return tag in self._tags_v2 or tag in self._tagdata
 
-    if bytes is str:
+    if not py3:
         def has_key(self, tag):
             return tag in self
 
@@ -528,7 +529,7 @@ class ImageFileDirectory_v2(collections.MutableMapping):
 
     def _setitem(self, tag, value, legacy_api):
         basetypes = (Number, bytes, str)
-        if bytes is str:
+        if not py3:
             basetypes += unicode,
 
         info = TiffTags.lookup(tag)
@@ -549,14 +550,14 @@ class ImageFileDirectory_v2(collections.MutableMapping):
                 elif all(isinstance(v, float) for v in values):
                     self.tagtype[tag] = 12
                 else:
-                    if bytes is str:
-                        # Never treat data as binary by default on Python 2.
-                        self.tagtype[tag] = 2
-                    else:
+                    if py3:
                         if all(isinstance(v, str) for v in values):
                             self.tagtype[tag] = 2
+                    else:
+                        # Never treat data as binary by default on Python 2.
+                        self.tagtype[tag] = 2
 
-        if self.tagtype[tag] == 7 and bytes is not str:
+        if self.tagtype[tag] == 7 and py3:
             values = [value.encode("ascii", 'replace') if isinstance(
                       value, str) else value]
 
@@ -1503,7 +1504,7 @@ def _save(im, fp, filename):
             if tag not in TiffTags.LIBTIFF_CORE:
                 continue
             if tag not in atts and tag not in blocklist:
-                if isinstance(value, unicode if bytes is str else str):
+                if isinstance(value, str if py3 else unicode):
                     atts[tag] = value.encode('ascii', 'replace') + b"\0"
                 elif isinstance(value, IFDRational):
                     atts[tag] = float(value)
diff --git a/src/PIL/WmfImagePlugin.py b/src/PIL/WmfImagePlugin.py
index 173ddb25b..213584497 100644
--- a/src/PIL/WmfImagePlugin.py
+++ b/src/PIL/WmfImagePlugin.py
@@ -23,13 +23,14 @@ from __future__ import print_function
 
 from . import Image, ImageFile
 from ._binary import i16le as word, si16le as short, i32le as dword, si32le as _long
+from ._util import py3
 
 
 __version__ = "0.2"
 
 _handler = None
 
-if str != bytes:
+if py3:
     long = int
 
 
diff --git a/src/PIL/_binary.py b/src/PIL/_binary.py
index b15f796c0..7e0d560b5 100644
--- a/src/PIL/_binary.py
+++ b/src/PIL/_binary.py
@@ -12,19 +12,20 @@
 #
 
 from struct import unpack, pack
+from ._util import py3
 
-if bytes is str:
-    def i8(c):
-        return ord(c)
-
-    def o8(i):
-        return chr(i & 255)
-else:
+if py3:
     def i8(c):
         return c if c.__class__ is int else c[0]
 
     def o8(i):
         return bytes((i & 255,))
+else:
+    def i8(c):
+        return ord(c)
+
+    def o8(i):
+        return chr(i & 255)
 
 
 # Input, le = little endian, be = big endian
diff --git a/src/PIL/_util.py b/src/PIL/_util.py
index 51c6f6887..6618c625f 100644
--- a/src/PIL/_util.py
+++ b/src/PIL/_util.py
@@ -1,17 +1,19 @@
-import os
+import os, sys
 
-if bytes is str:
-    def isStringType(t):
-        return isinstance(t, basestring)
+py3 = sys.version_info.major >= 3
 
-    def isPath(f):
-        return isinstance(f, basestring)
-else:
+if py3:
     def isStringType(t):
         return isinstance(t, str)
 
     def isPath(f):
         return isinstance(f, (bytes, str))
+else:
+    def isStringType(t):
+        return isinstance(t, basestring)
+
+    def isPath(f):
+        return isinstance(f, basestring)
 
 
 # Checks if an object is a string, and that it points to a directory.