Adding a low molecular weight (or alternatively, high melt flow rate), functionalized, isotactic polypropylene (iPP) to a hot melt adhesive (HMA), composition containing a propylene-butene-1, and/or a propylene-ethylene amorphous poly alpha olefin (APAO) copolymer, in addition to other co-adjuvants (such as a tackifier or a plasticizer), results in an APAO-based HMA that shows improved tensile strength and bonding properties, over an HMA that contains only the propylene-butene-1 and/or the propylene-ethylene APAO copolymer (with or without a tackifier and/or a plasticizer).