diff -r 67d9595a833c Lib/test/test_exceptions.py
--- a/Lib/test/test_exceptions.py	Fri Mar 02 22:54:03 2012 +0100
+++ b/Lib/test/test_exceptions.py	Fri Mar 02 20:38:27 2012 -0300
@@ -38,7 +38,7 @@
         try:
             try:
                 import marshal
-                marshal.loads('')
+                marshal.loads(b'')
             except EOFError:
                 pass
         finally:
diff -r 67d9595a833c Lib/test/test_marshal.py
--- a/Lib/test/test_marshal.py	Fri Mar 02 22:54:03 2012 +0100
+++ b/Lib/test/test_marshal.py	Fri Mar 02 20:38:27 2012 -0300
@@ -201,7 +201,7 @@
                 pass
 
     def test_loads_recursion(self):
-        s = 'c' + ('X' * 4*4) + '{' * 2**20
+        s = b'c' + (b'X' * 4*4) + b'{' * 2**20
         self.assertRaises(ValueError, marshal.loads, s)
 
     def test_recursion_limit(self):
@@ -274,6 +274,11 @@
             finally:
                 support.unlink(support.TESTFN)
 
+    def test_loads_reject_unicode_strings(self):
+        # Issue #14177: marshal.loads() should not accept unicode strings
+        unicode_string = 'T'
+        self.assertRaises(TypeError, marshal.loads, unicode_string)
+
 
 def test_main():
     support.run_unittest(IntTestCase,
diff -r 67d9595a833c Python/marshal.c
--- a/Python/marshal.c	Fri Mar 02 22:54:03 2012 +0100
+++ b/Python/marshal.c	Fri Mar 02 20:38:27 2012 -0300
@@ -1370,7 +1370,7 @@
 "dumps(value[, version])\n\
 \n\
 Return the string that would be written to a file by dump(value, file).\n\
-The value must be a supported type. Raise a ValueError exception if\n\
+The value must support the buffer interface. Raise a TypeError exception if\n\
 value has (or contains an object that has) an unsupported type.\n\
 \n\
 The version argument indicates the data format that dumps should use.");
@@ -1384,7 +1384,7 @@
     char *s;
     Py_ssize_t n;
     PyObject* result;
-    if (!PyArg_ParseTuple(args, "s*:loads", &p))
+    if (!PyArg_ParseTuple(args, "y*:loads", &p))
         return NULL;
     s = p.buf;
     n = p.len;