Cheryl Hines and Lindsay Lohan
Stephen Lovekin/Getty; Jordan Strauss/WireImage
07/13/2008 at 02:00 PM EDT
Cheryl Hines can't curb her enthusiasm for working with Lindsay Lohan
on the set of their film Labor Pains
"I have had a great time shooting with her, and when we have scenes together we have a lot of fun improvising," Hines, 42, told PEOPLE Saturday at the Los Angeles premiere of her new animated film Space Chimps
, to which she lends her voice as astronaut chimp Lieutenant Luna. "It usually ends in a big laugh fest, and they have to cut because we can't talk anymore."
Hines, who has starred with Larry David in the HBO hit Curb Your Enthusiasm
since 2000, insists she expected nothing less from the 22-year-old star – even in light of Lohan's past troubles on set
"It was what I expected," Hines said of Lohan's professionalism. "I honestly expected that she's gotten herself together, and really wanted to work and that's what she's showing us. I'm very proud of her."
Lohan's movie career has been stalled by stints in rehab
, but a Labor Pains producer confirmed to PEOPLE in June that those days appear to be over – Lohan showed up for work June 9 on the L.A. location and has consistently been early and well-prepared for the grueling 12-hour shoots.