The present invention relates to a variant pullulanase, wherein the pullulanase comprises at least the following combination of substitutions: N368G+N393A+Q431E+L432F+A492A,S+N610R+G624S+T631S+S632C, and optionally further comprises N222P+Q252A+Q256R; wherein the variant has pullulanase activity, and wherein the variants have at least 85%, at least 90%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99%, but less than 100% sequence identity to the polypeptide of SEQ ID NO: 3. Further aspect the present invention relates to a process for liquefying starch-containing material at a temperature above the initial gelatinization temperature using an alpha-amylase and a thermo-stable pullulanase of the invention.