In a water-redispersible polymer powder—the polymer is at least one esterified cellulose ether comprising (i) groups of the formula —C(O)—R—COOA or (ii) a combination of aliphatic monovalent acyl groups and groups of the formula —C(O)—R—COOA, wherein R is a divalent aliphatic or aromatic hydrocarbon group and A is hydrogen or a cation, and—the polymer powder comprises from 0.05 to 20 percent of at least one salt of a fatty acid, based on the weight of the esterified cellulose ether(s).