diff --git a/src/trezor/wire/wire_codec.py b/src/trezor/wire/wire_codec.py
index 22a2669a8b..9b2d4ec35e 100644
--- a/src/trezor/wire/wire_codec.py
+++ b/src/trezor/wire/wire_codec.py
@@ -115,7 +115,10 @@ Pass report payloads as `memoryview` for cheaper slicing.
     msg_footer = data_tail[:_MSG_FOOTER_LEN]
     if len(msg_footer) < _MSG_FOOTER_LEN:
         data_tail = yield  # read report with the rest of checksum
-        msg_footer += data_tail[:_MSG_FOOTER_LEN - len(msg_footer)]
+        footer_tail = data_tail[:_MSG_FOOTER_LEN - len(msg_footer)]
+        if isinstance(msg_footer, memoryview):
+            msg_footer = bytearray(msg_footer)
+        msg_footer.extend(footer_tail)
 
     data_checksum, = parse_message_footer(msg_footer)
     if data_checksum != checksum: