Stable synchronous pumping of a Rh6G-DODCI femtosecond dye laser by a frequency-doubled continuously modelocked Nd:YAG laser is achieved. A group-velocity-compensated linear cavity terminates in an antiresonant ring containing a saturable absorber. Critical variations of pulse characteristics with cavity-length detuning are avoided by an active stabilization of the cavity length. As the error signal, we use the variation of the dye-laser's central wavelength with the cavity mismatch.