Compile warning v0.8.3 fastq_qualscale

[cppa]

Hello,

when compiling I get the following warning:

fastq-qscale.c: In function ‘fastq_qualscale’:
fastq-qscale.c:61:21: warning: ‘compat_scales’ may be used uninitialized in this function [-Wmaybe-uninitialized]
     return x && !(x & (x - 1));
                     ^
fastq-qscale.c:89:14: note: ‘compat_scales’ was declared here
     uint32_t compat_scales;

My CFLAGS variable:

make CFLAGS='-std=gnu99 -Wall -Wextra -g -O3 -D_POSIX_C_SOURCE=200809' How can this warning be removed?