Making 2 story window safe

Brilea

My 2 yr old sons new room is on the second floor of our new house. It has a window that’s super low to the floor. Only about a foot off the floor. I know that he won’t be able to open it. But I’m scared to death he’s gonna get on the window seal or him and his brother might rough house in the there and one of them is gonna break it and fall out the window. It’s a good 15 foot drop. Is there anything I can get that will make sure that won’t happen? Or am I being ridiculous.