When I use MathML's <msqrt> function, I get white-space in underoot. Please suggest, how to fix it in Prince xml coding.

<math xmlns="http://www.w3.org/1998/Math/MathML" class="equation"><mi>U</mi><mfenced><mi>M</mi></mfenced><mo>=</mo><msqrt><mi>M</mi></msqrt><mtext>.</mtext></math>

1. Capture.PNG‎ 8.6 kB

Do you know which fonts are used in the PDF? Or which platform are you running Prince on?