diff -r ab7f57e92629 Lib/fileinput.py
--- a/Lib/fileinput.py	Mon Apr 14 12:16:18 2014 -0400
+++ b/Lib/fileinput.py	Tue Apr 15 12:36:37 2014 -0400
@@ -320,7 +320,10 @@
             self._backupfilename = 0
             if self._filename == '-':
                 self._filename = '<stdin>'
-                self._file = sys.stdin
+                if 'b' in self._mode:
+                    self._file = sys.stdin.buffer
+                else:
+                    self._file = sys.stdin
                 self._isstdin = True
             else:
                 if self._inplace:
diff -r ab7f57e92629 Lib/test/test_fileinput.py
--- a/Lib/test/test_fileinput.py	Mon Apr 14 12:16:18 2014 -0400
+++ b/Lib/test/test_fileinput.py	Tue Apr 15 12:36:37 2014 -0400
@@ -19,11 +19,12 @@
 except ImportError:
     gzip = None
 
-from io import StringIO
+from io import BytesIO, StringIO
 from fileinput import FileInput, hook_encoded
 
 from test.support import verbose, TESTFN, run_unittest, check_warnings
 from test.support import unlink as safe_unlink
+from unittest import mock
 
 
 # The fileinput module has 2 interfaces: the FileInput class which does
@@ -232,6 +233,13 @@
         finally:
             remove_tempfiles(t1)
 
+    def test_stdin_binary_mode(self):
+        with mock.patch('sys.stdin') as m_stdin:
+            m_stdin.buffer = BytesIO(b'spam, bacon, sausage, and spam')
+            fi = FileInput(files=['-'], mode='rb')
+            lines = list(fi)
+            self.assertEqual(lines, [b'spam, bacon, sausage, and spam'])
+
     def test_file_opening_hook(self):
         try:
             # cannot use openhook and inplace mode