# 0058: Invalid parameter

A [command](https://docs.sannybuilder.com/language/instructions/built-in-commands) has been given an invalid parameter. For example, it may happen if a number is used in [`SQR`](https://docs.sannybuilder.com/language/instructions/built-in-commands#sqr), while the compiler expects a [variable](https://docs.sannybuilder.com/language/data-types/variables).

**Possible solutions:** check the command and use valid syntax:

```
sqr(10) // error, variable expected
sqr($var) // OK
```