For an integer m ě 2, a partition λ " pλ1, λ2, . . .q is called m-falling, a notion introduced by Keith, if the least nonnegative residues mod m of λi's form a nonincreasing sequence. We extend a bijection originally due to the third author to deduce a lecture hall theorem for such m-falling partitions. A special case of this result gives rise to a finite version of Pak-Postnikov's pm, cq-generalization of Euler's theorem. Our work is partially motivated by a recent extension of Euler's theorem for all moduli, due to Keith and Xiong. We note that their result actually can be refined with one more parameter.