Defining my operator failed

fahr.p6

class Fahrenheit {
    has Real $.temperature is required;

    method infix:<+>(Fahrenheit:D $a, Fahrenheit:D $b) {
        return Fahrenheit.new( temperature => $a.temperature + $b.temperature );
    }
}

my $t1 = Fahrenheit.new( temperature => 22 );
my $t2 = Fahrenheit.new( temperature => 34 );
say $t1 + $2;

# Cannot call Numeric(Fahrenheit: ); none of these signatures match:
#  (Mu:U \v: *%_)
# in block <unit> at int.p6 line 11

Per arnsholt, I've tried this, but it failed with the same error:

class Fahrenheit {
    has Real $.temperature is required;
}

multi sub infix:<+>(Fahrenheit:D $a, Fahrenheit:D $b) {
    return Fahrenheit.new( temperature => $a.temperature + $b.temperature );
}

my $t1 = Fahrenheit.new( temperature => 22 );
my $t2 = Fahrenheit.new( temperature => 34 );
say $t1 + $2;

As pointed out, $2 was a typo :)