diff -r 52ab9e1ff46a Lib/imghdr.py
--- a/Lib/imghdr.py	Sun Feb 16 14:17:28 2014 -0500
+++ b/Lib/imghdr.py	Sat Feb 22 11:19:20 2014 +0200
@@ -10,7 +10,7 @@
     f = None
     try:
         if h is None:
-            if isinstance(file, str):
+            if isinstance(file, (str, bytes)):
                 f = open(file, 'rb')
                 h = f.read(32)
             else:
diff -r 52ab9e1ff46a Lib/test/test_imghdr.py
--- a/Lib/test/test_imghdr.py	Sun Feb 16 14:17:28 2014 -0500
+++ b/Lib/test/test_imghdr.py	Sat Feb 22 11:19:20 2014 +0200
@@ -72,8 +72,6 @@
             imghdr.what(None)
         with self.assertRaises(TypeError):
             imghdr.what(self.testfile, 1)
-        with self.assertRaises(AttributeError):
-            imghdr.what(os.fsencode(self.testfile))
         with open(self.testfile, 'rb') as f:
             with self.assertRaises(AttributeError):
                 imghdr.what(f.fileno())
@@ -127,5 +125,11 @@
             with self.assertRaises(OSError) as cm:
                 imghdr.what(stream)
 
+    def test_bytes_file(self):
+        for filename, expected in TEST_FILES:
+            filename = findfile(filename, subdir="imghdrdata")
+            self.assertEqual(imghdr.what(os.fsencode(filename)),
+                             expected)
+
 if __name__ == '__main__':
     unittest.main()