Mister Softee is taking a hard line against a competitor who's using the company's iconic jingle to sell his ice cream. Michael Scotto filed the following report.

In New York, it's the theme song of happiness, announcing that ice cream is no farther than the curb.

"It's like Christmas," said Nathaniel Johnson, a Mister Softee truck owner. "You hear our jingle, you want ice cream."

Johnson has been selling Mister Softee for nearly 30 years.

"Soft serve is the most popular," he said.

Lately, though, he says business has gotten tougher because of imposters who ride around trucks that look and sound a whole lot like Mister Softee.

"If you're going to use what I use in order to attract customers, then you're robbing from me," Johnson said.

The ice cream giant is cracking down on the fakes, filing suit last week against a man who tools around in an ice cream truck while playing the trademarked Mister Softee jingle.

Craig Zoly runs a Mister Softee depot in Queens.

"What they do is, they give Mister Softee a bad name, actually, because they're pretending to be us," Zoly said.

Such battles between Mister Softee and the knockoffs are not new, but there are more of them now. Zoly says he has at least three active lawsuits against imposters in Queens alone. An ice cream war, if you will.   

Selling Mister Softee ice cream isn't cheap. Drivers pay about $130,000 for the truck and about $3,100 a year in royalties to Mister Softee.  

Many of the imposters are former Mister Softee drivers who went rogue, using the brand without paying the fees.

NY1 stopped by the Long Island City depot where some of these competitors are based, but they closed the gate on us.

When we asked for one of the men at the center of the battle, a man resembling him told us he wasn't in.

"They're not coming today. Tomorrow, they'll be here," the man said.

Back at Mister Softee, Johnson pointed out that you can only get the real stuff from trucks like his.

"All of our stuff is protected by Mister Softee," Johnson said.

There's concern, though, that if Mister Softee's competitors keep it up, ice cream lovers will have a hard time telling the difference.