diff --git a/Lib/test/test_bytes.py b/Lib/test/test_bytes.py
index e5c7ccd..11cd801 100644
--- a/Lib/test/test_bytes.py
+++ b/Lib/test/test_bytes.py
@@ -517,6 +517,8 @@ class BytesTest(BaseBytesTest):
                          b'c:\xff')
         self.assertEqual(PyBytes_FromFormat(b's:%s', c_char_p(b'cstr')),
                          b's:cstr')
+        self.assertEqual(PyBytes_FromFormat(b'y:%y', py_object(b'bytes')),
+                         b'y:bytes')
 
 
 class ByteArrayTest(BaseBytesTest):
diff --git a/Objects/bytesobject.c b/Objects/bytesobject.c
index ba33608..0356e52 100644
--- a/Objects/bytesobject.c
+++ b/Objects/bytesobject.c
@@ -215,6 +215,13 @@ PyBytes_FromFormatV(const char *format, va_list vargs)
                  */
                 n += 19;
                 break;
+            case 'y':
+            {
+                PyObject *obj = va_arg(count, PyObject *);
+                assert(obj && PyBytes_Check(obj));
+                n += PyBytes_GET_SIZE(obj);
+                break;
+            }
             default:
                 /* if we stumble upon an unknown
                    formatting code, copy the rest of
@@ -323,6 +330,14 @@ PyBytes_FromFormatV(const char *format, va_list vargs)
                 }
                 s += strlen(s);
                 break;
+            case 'y':
+            {
+                PyObject *obj = va_arg(vargs, PyObject *);
+                Py_ssize_t size = PyBytes_GET_SIZE(obj);
+                memmove(s, PyBytes_AS_STRING(obj), size);
+                s += size;
+                break;
+            }
             case '%':
                 *s++ = '%';
                 break;