TYPO3.Fluid

In my extension i have a flexform where i can configure the attributes of every formfield.
I use the IF inline syntax in the "view" to achieve this.

This works well for all attributes except for the multiple attribute.

Example:

<f:form.Select 
    property="{fieldHelper.name}" 

     options="{fieldHelper.config.options}" 

    id="{form.name}_{fieldHelper.name}" 

    disabled="{f:if(condition: fieldHelper.config.disabled, then: 'disabled')}" 
    multiple="{f:if(condition: fieldHelper.config.multiple, then: 'multiple')}" 

    accesskey="{fieldHelper.config.accesskey}" 
    tabindex="{f:if(condition: fieldHelper.config.tabindex, then: fieldHelper.config.tabindex)}" 
/>

The problem is in the SelectViewHelper it checks only if the attribute is given not have a value.
Lines: 111, 125, 213
if ($this->arguments->hasArgument('multiple')) {

this syntax is unfortunately not working:

<f:form.Select 
    {f:if(condition: fieldHelper.config.multiple, then: 'multiple="multiple"')}
/>