# M0150

This error means you supplied a mutable record field (declared with `var`) where an immutable record field (specified without `var`) was expected.

Erroneous code example:

```motoko
{ var name = "Fred" } : { name : Text }
```

If you encounter this error, you should probably omit `var`:

```motoko
{ name = "Fred" } : { name : Text }
```