Always tidy up before calling the cops — it’s a lesson that Michael Cokley learned the hard way.

Late last year, he called 911 to report a gunpoint home-invasion robbery.

As he described the ordeal to them at his Far Rockaway, Queens, apartment, cops smelled the distinctive aroma of marijuana and saw heroin out in the open, police say.

After getting a search warrant, the cops allegedly discovered 34 grams of heroin, 91 glassine envelopes, four marijuana grinders and an electronic scale.

Cokley now faces federal heroin-distribution charges. He’s pleaded not guilty.