Mayor Bill de Blasio Thursday signed a bill nicknamed "Avonte's Law" in memory of a severely autistic teenage boy who left his Queens school through a door that had no alarm and was later found dead.

Under the law, passed July 24 by the City Council, the city's Department of Education must consider whether alarms are needed on all schools serving students with special needs, as well as elementary schools. Alarms must be installed if officials determine they're necessary.

The evaluation must be done by May 30, 2015.

"We're committed to making sure our schools have more tools at their disposal to keep our children safe," de Blasio said before signing the legislation.

Avonte Oquendo, a 14-year-old who could not communicate, left the Long Island City schoolhouse in October and his remains were found by the East River in January. The cause of death could not be determined by the medical examiner.

Avonte's mother and grandmother attended the bill signing but did not speak publicly. The family has hired an attorney to sue the city.

De Blasio also signed bills raising the income threshold for disabled recipients of a rent subsidy and increasing online access to city information.