MAX V GCLK Impedance

Hi, I'm using a MAX V device with a 100Mhz CLK on the GCLK input. We need to understand the impedance of the GCLK input such that we can match the crystal oscillator module to the MAX V input. In the MAX V datasheet the only information I can find WRT to the input impedance is a reference to a maximum capacitance of 8pF. My Crystal has a 25 Ohm output matched to 50 ohm transmission line. Obviously I don't want to get reflections or bad clock edges, so matching the impedance's between the parts seems very sensible.