Check if the match fails. $& and the other magic regex variables aren't cleared on failure:

my $foo = "bar";
$foo =~ /ar/;
print "Got $&!\n";
$foo =~ /az/;
print "Got $&!\n";
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Throw an if block or an and in there and you'll be set:

if ($foo =~ /ar/) {
    print "Got $&!\n";
}
$foo =~ /az/ and print "Got $&!\n";
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