MICHIGAN: Maybe Justin Bieber’s caravan should have cleaned up a little before heading to Motown.

Marijuana and drug paraphernalia were seized from one of the pop star’s tour buses at the U.S.-Canada border on its way into Michigan last night, authorities confirm to E! News.

Bieber was not on the bus in question when it was stopped. Apparently it was a drug-sniffing dog that sensed there was contraband aboard.

“On July 28, a commercial touring bus attempted to enter the U.S. through Detroit via the Ambassador Bridge,” Chief Customs and Border Protection Officer Ken Hammond said in a statement to E! News.

“The tour bus, associated with musician Justin Bieber, was en route to a concert scheduled later Sunday night in Detroit. During the secondary inspection, a K-9 alerted to the presence of drugs and a subsequent search of the bus revealed marijuana and drug paraphernalia. Justin Bieber was not on the bus.