Due to issue in SyntaxHighlighter Evolved plugin & symbol is output as & what makes code unreadable.

kagg_syntaxhighlighter_precode.php

<?php
/**
 * Filter to fix issue in SyntaxHighlighter Evolved plugin.
 *
 * @param string $code Code to format.
 * @param array $atts Attributes.
 * @param string $tag Tag.
 *
 * @return string
 */
function kagg_syntaxhighlighter_precode( $code, $atts, $tag ) {
	if ( 'code' === $tag ) {
		$code = wp_specialchars_decode( $code );
	}

	return $code;
}

add_filter( 'syntaxhighlighter_precode', 'kagg_syntaxhighlighter_precode', 10, 3 );

Nice little code snippet, but how do you make SyntaxHighlighter Evolved use it?

Thank you @arwidmark. I just add this snippet to functions.php of the theme.