# Error code E0384

An immutable variable was reassigned.

Erroneous code example:

ⓘ

    fn main() {
        let x = 3;
        x = 5; // error, reassignment of immutable variable
    }

Run

By default, variables in Rust are immutable. To fix this error, add the keyword `mut` after the keyword `let` when declaring the variable. For example:

    fn main() {
        let mut x = 3;
        x = 5;
    }

Run

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