If you wanted to bring a human-like robot on your next Southwest flight, that plan has been grounded.

Southwest Airlines just updated its travel policy to prohibit passengers from bringing humanoid or animal-like robots onto flights — both in the cabin and as checked baggage, USA Today reported.

The policy change came after an incident that went viral online that involved a humanoid robot named Stewie that traveled on a Southwest flight from Las Vegas to Dallas, according to USA Today.

Stewie’s owner, Dallas entrepreneur Aaron Mehdizadeh, bought the 3.5-foot robot its own seat instead of shipping it as cargo, CBS News Texas reported. Mehdizadeh owns The Robot Studio, which rents humanoid robots for events.

To get to the plane, the robot Stewie walked through the airport, which USA Today said drew attention from passengers and flight attendants.

A “human-like robot” means robot designed to resemble or imitate a human in its appearance, movement or behavior, and an “animal-like robot” is similarly defined as a robot designed to imitate an animal, according to Southwest definition.

The Dallas-based airline said the restriction applies “regardless of size or purpose,” USA Today reported.

However, Southwest Airlines said all other robots, including toys, are still permitted if they fit inside a carry-on-sized bag and comply with existing battery restrictions.

Southwest said the updated policy surrounding humanoid robots is tied to concerns surrounding lithium-ion batteries commonly used in them — as lithium-ion batteries have previously caused onboard fires.

Stewie the robot had a smaller battery installed in order to board and meet security requirements, USA Today reported. Mehdizadeh said this smaller battery was comparable to one found in a laptop.

However, airline employees were initially unsure how to handle the robot onboard because it effectively counted as a carry-on item and could not remain in a passenger seat, NBC 5 Dallas-Fort Worth reported.

The airline moved Stewie to a window seat and removed the robot’s battery before the flight took off.

The robot, speaking through a programmed voice, joked that it had “the perfect window seat.”