Macro does not display anything when used in src attribute for image

We have a latte macro like this:

	public function ___binToImage($image)
	{
		return "data:{$image->type};base64,{$image->data}";
	}

And use it in template like this:

<img src="{$product->image|binToImage}">

And it does not work.

Although this is expected

<img src="data:...;base64,...">

Generated html looks like this

<img src="">

If I do anything from this:

• change the attribute to something else (src2)
• display the macro out of the attribute (<p>{$product->image|binToImage}</p>)
• change the contents of the string returned from macro (return “foobar”)

it works as expected. There has to be some escaping involved but using noescape did not help.