It had been suggested that the 25-year-old's international career was over after he was left out of the squad for Wednesday's clash with Australia, but Houston has denied such claims.
"He said the door was always open for Lee Wallace to get in the squad. He wants to have a look at Danny Fox as well. Lee Wallace is very much part of Craig Levein's plans, trust me," he told the BBC.
Wallace has six international caps to his name.