The invention pertains to an infant formula powder composition comprising micronized lactose or lactose microcrystals (i) smaller than 30 micrometer, and/or (ii) of which at least 80 % has a size less than 20 micrometer, and/or (iii) at least 80 % has a size less than 10 micrometer, and/or (iv) having a median particle size D50 below 10 micrometer. The invention also pertains to the use of micronized lactose or lactose microcrystals for improving flow of an infant formula powder composition.