Nowadays, it’s fine to end a sentence with a preposition.

Many of us grew up being taught that ending a sentence with a preposition was a no-no. The rules have changed, and once the sentence structure is otherwise good, you can ignore the old-time rule.

“What are you sitting on?”

“This is the movie I told you about”

In the two sentences above which both end in prepositions, they sound more natural than: “On what are you sitting?” and “This is the movie about which I told you.”

While the latter two sentences are grammatically correct, modern usage also allows the first two examples where the sentences end in prepositions.