I called maq with the following command:
maq fastq2bfq -n 2000000 fastq/s_1_0010_reads1.fastq s_1_0010.1.bfq
And it aborted with a segmentation fault
It took me some time to find that the problem was a typing error in the filename.
The problems is caused in the module seq.c. There the input file is opened and accessed without checking if the opening was successful. Here is probably an assertion is missing like in the other modules handling input files.