diff -u b/Objects/bytesobject.c b/Objects/bytesobject.c
--- b/Objects/bytesobject.c	Mon Jan 20 15:26:06 2014 -0600
+++ b/Objects/bytesobject.c	Mon Jan 20 15:26:05 2014 -0600
@@ -1426,6 +1426,48 @@
 }
 
 static PyObject*
+bytes_compatible_compare(PyObject *a, PyObject *b, int op)
+{
+    PyObject *result;
+    if (PyBytes_Check(a)) {
+        a = PyUnicode_FromEncodedObject(a, NULL, "strict");
+        if (a == NULL && PyErr_ExceptionMatches(PyExc_UnicodeDecodeError)) {
+            PyErr_Clear();
+            goto abort;
+        }
+    }
+    else {
+        Py_INCREF(a);
+    }
+    if (PyBytes_Check(b)) {
+        b = PyUnicode_FromEncodedObject(b, NULL, "strict");
+        if (b == NULL && PyErr_ExceptionMatches(PyExc_UnicodeDecodeError)) {
+            Py_DECREF(a);
+            PyErr_Clear();
+            goto abort;
+        }
+    }
+    else {
+        Py_INCREF(b);
+    }
+    if (PyErr_Warn(PyExc_BytesWarning,
+                     "Comparison between bytes and str") < 0) {
+        Py_DECREF(a);
+        Py_DECREF(b);
+        return NULL;
+    }
+    result = PyObject_RichCompare(a, b, op);
+    Py_DECREF(a);
+    Py_DECREF(b);
+    return result;
+
+abort:
+    result = Py_NotImplemented;
+    Py_INCREF(result);
+    return result;
+}
+
+static PyObject*
 bytes_richcompare(PyBytesObject *a, PyBytesObject *b, int op)
 {
     int c;
@@ -1435,15 +1477,17 @@
 
     /* Make sure both arguments are strings. */
     if (!(PyBytes_Check(a) && PyBytes_Check(b))) {
-        if (Py_BytesWarningFlag && (op == Py_EQ || op == Py_NE) &&
-            (PyObject_IsInstance((PyObject*)a,
-                                 (PyObject*)&PyUnicode_Type) ||
-            PyObject_IsInstance((PyObject*)b,
-                                 (PyObject*)&PyUnicode_Type))) {
+        int have_str = (PyObject_IsInstance((PyObject*)a,
+                                            (PyObject*)&PyUnicode_Type) ||
+                        PyObject_IsInstance((PyObject*)b,
+                                            (PyObject*)&PyUnicode_Type));
+        if (Py_BytesWarningFlag && (op == Py_EQ || op == Py_NE) && have_str) {
             if (PyErr_WarnEx(PyExc_BytesWarning,
                         "Comparison between bytes and string", 1))
                 return NULL;
         }
+	if (Py_BytesComplatibleFormatFlag)
+            return bytes_compatible_compare((PyObject *)a, (PyObject *)b, op);
         result = Py_NotImplemented;
     }
     else if (a == b) {