diff --git a/adafruit_ble_midi.py b/adafruit_ble_midi.py
index 4d6dd45..f29e1bc 100644
--- a/adafruit_ble_midi.py
+++ b/adafruit_ble_midi.py
@@ -87,7 +87,7 @@ def readinto(self, buf, length):
 
         Returns the number of bytes written into ``buf``."""
         if self._in_buffer is None:
-            self._in_buffer = bytearray(self._raw.packet_size)
+            self._in_buffer = bytearray(self._raw.incoming_packet_length)
         i = 0
         while i < length:
             if self._in_index < self._in_length: