Marketo Adding Space in MSO Comments

I’ve been working on fluid responsive emails and I found that Marketo adds a space in in the MSO comments that seems to keep Outlook from seeing the [if mso] code. I tested the same HTML in Marketo and MailChimp. The code works perfect in MailChimp, but breaks when sent through Marketo.

Here is where the problem is happening (highlighted).

Before Marketo: <!--[if mso]>

After Marketo: <!-- [if mso]>

Marketo is adding that additional space, which seems to be causing Outlook to ignore the comment instead of reading it as Outlook specific code. I tested it both ways in Litmus and that's what happens. Does anyone know how to keep Marketo from adding that space?