Amazon is warning employees not to wear clothing with company logos, and telling them to keep their badges out of sight as hundreds of people loyal to the hacktivist group Anonymous plan to march on the tech giant’s Seattle headquarters this afternoon.

The company’s regional security manager sent the message to Amazon employees in advance of the “Million Mask March.” The march is described as a global day of action in which people wearing Guy Fawkes masks, the symbol of Anonymous, protest corruption and injustice in a wide range of corporate and government institutions.

“Please remember to not wear anything that has Amazon logos and keep your badges covered or put away and out of site,” reads the internal Amazon memo, asking employees to report any issues to security immediately.

A Facebook message from the Seattle group reads, “On November 5th, we will be rallying at Westlake Park in Seattle at 2pm, and then marching to the Federal Courthouse at 3pm, and from there, we shall march to Amazon for some serious lulz!. Teach-ins and rallies will continue throughout the remainder of the day.”

The Amazon memo notes, “It is unclear what the group intends to do vis-à-vis Amazon, but the purported organizer is an individual with known anarchist views and a desire to engage in direct action.”

More than 600 people had signed up via Facebook to participate in the march in Seattle as of this morning.