ZF2 console route with minus number as parameter

gistfile1.php

Not sure if this is an issue or expected:

I have the following console route: 

return [
    'console' => [
        'router' => [
            'routes' => [
                'set-user-starting-balance' => [
                    'options'   => [
                        'route'     => 'set user init-balance <userEmail> <balance>',
                        'defaults'  => [
                            'controller' => 'JhFlexiTime\Controller\RunningBalanceCli',
                            'action'     => 'set-user-starting-balance'
                        ],
                        'constraints' => array(
                            //regex to match decimal and floats
                            'balance' => '/^-?\d{1,4}(.\d{1,2})?$/'
                        ),
                    ],
                ],
            ]
        ]
    ]
];

This route matches fine for the following commands:

php public/index.php set user init-balance aydin@hotmail.co.uk 2.25
php public/index.php set user init-balance aydin@hotmail.co.uk 1
php public/index.php set user init-balance aydin@hotmail.co.uk 0.25

The following doesn't work:

//note the dash, "-2", minus 2
php public/index.php set user init-balance aydin@hotmail.co.uk -2

And you can see the Regular Expression works here: http://regexr.com/38spt

When I say it doesn't work, the following error is returned:
"Reason for failure: Invalid arguments or no arguments provided"

I'm assuming this maybe has something do with: https://github.com/zendframework/zf2/blob/master/library/Zend/Console/RouteMatcher/DefaultRouteMatcher.php 
matching that parameter as an option or something?