Elon Musk said demand for Tesla Inc. vehicles is so high that production needs to increase as much as possible for the rest of December.

Without giving specific numbers, Musk sent a short email on Friday to workers encouraging them to push output to the maximum possible during the holiday season. The company has a target of delivering 500,000 cars this year, which would be a major milestone for the Palo Alto, California-based maker of electric vehicles and clean-energy products.

“We are fortunate to have the high-class problem of demand being quite a bit higher than production this quarter,” Musk wrote in the email viewed by Bloomberg. “Please send me a note directly if you see ways to improve output, but feel that your voice is not being heard.”

Musk has a history of sending emails toward the end of the quarter urging employees to surge production or volunteer to help with deliveries, and the emails typically leak and serve as a signal to investors. Tesla’s shares have surged more than 600% this year amid a streak of consecutive quarterly profits. The company will vault into the S&P 500 Index on Dec. 21.

Tesla said it would meet its goal of delivering half a million cars worldwide this year during October’s earnings report. The company needs to deliver more than 181,000 cars in the last three months of the year to hit that mark, which would be a 30% jump over the previous quarter. The push will largely depend on increased production at its Shanghai factory and higher output of its Model Y, the newest car in its lineup.