diff --git a/adafruit_ble_eddystone/__init__.py b/adafruit_ble_eddystone/__init__.py
index fe3cd14..e4d47dc 100644
--- a/adafruit_ble_eddystone/__init__.py
+++ b/adafruit_ble_eddystone/__init__.py
@@ -68,7 +68,7 @@ def __set__(self, obj, value):
                 raise ValueError("Value length does not match")
             obj.eddystone_frame[self._offset : self._offset + self._length] = value
         else:
-            obj.eddystone_frame = obj.eddystone_frame[: self._offset] + value
+            obj.eddystone_frame = bytes(obj.eddystone_frame[: self._offset]) + value
 
 
 class EddystoneFrameStruct(EddystoneFrameBytes):