# E4177

Extracting bytes sequence using bitstring pattern must be byte-aligned.

## Erroneous example

```{literalinclude} /sources/error_codes/4177_error/top.mbt
:language: moonbit
```

## Suggestion

Align the bit pattern to full bytes before extracting a byte sequence.

```{literalinclude} /sources/error_codes/4177_fixed/top.mbt
:language: moonbit
```