The present disclosure relates to modified antisense oligonucleotides. The nucleotides described herein are of 10 to 40 nucleobases and include a targeting sequence complementary to a target region within intron 1 of a pre-mRNA of the human alpha glucosidase (GAA) gene. The target region includes at least one additional nucleobase compared to the targeting sequence, wherein the at least one additional nucleobase has no complementary nucleobase in the targeting sequence, and wherein the at least one additional nucleobase is internal to the target region.