Failed to build installable wheels for some pyproject.toml based projects (fanc)

[zhaoxj2023]

Hi, I'm new to fanc and trying to use it, but I'm encountering an issue and not sure what's happening. The error output is quite long, so here are the last few lines.
Any insights would be greatly appreciated!

[
fanc/tools/sambam.c: In function ‘__pyx_pw_4fanc_5tools_6sambam_1natural_cmp’:
fanc/tools/sambam.c:2488:7: error: ‘for’ loop initial declarations are only allowed in C99 or C11 mode
for (Py_ssize_t i = __pyx_nargs; i < 2; i++) {
^
fanc/tools/sambam.c:2488:7: note: use option -std=c99, -std=gnu99, -std=c11 or -std=gnu11 to compile your code
fanc/tools/sambam.c:2517:3: error: ‘for’ loop initial declarations are only allowed in C99 or C11 mode
for (Py_ssize_t __pyx_temp=0; __pyx_temp < (Py_ssize_t)(sizeof(values)/sizeof(values[0])); ++__pyx_temp) {
^
fanc/tools/sambam.c:2527:19: error: redefinition of ‘__pyx_temp’
for (Py_ssize_t __pyx_temp=0; __pyx_temp < (Py_ssize_t)(sizeof(values)/sizeof(values[0])); ++__pyx_temp) {
^
fanc/tools/sambam.c:2517:19: note: previous definition of ‘__pyx_temp’ was here
for (Py_ssize_t __pyx_temp=0; __pyx_temp < (Py_ssize_t)(sizeof(values)/sizeof(values[0])); ++__pyx_temp) {
^
fanc/tools/sambam.c:2527:3: error: ‘for’ loop initial declarations are only allowed in C99 or C11 mode
for (Py_ssize_t __pyx_temp=0; __pyx_temp < (Py_ssize_t)(sizeof(values)/sizeof(values[0])); ++__pyx_temp) {
^
fanc/tools/sambam.c: In function ‘__Pyx_ParseKeywordsTuple’:
fanc/tools/sambam.c:4433:5: error: ‘for’ loop initial declarations are only allowed in C99 or C11 mode
for (Py_ssize_t pos = 0; pos < num_kwargs; pos++) {
^
fanc/tools/sambam.c: In function ‘__Pyx_PyCode_New’:
fanc/tools/sambam.c:7597:5: error: ‘for’ loop initial declarations are only allowed in C99 or C11 mode
for (Py_ssize_t i=0; i < var_count; i++) {
^
error: command '/public/software//compiler/gnu/4.9.1/bin/gcc' failed with exit code 1
[end of output]

note: This error originates from a subprocess, and is likely not a problem with pip.
ERROR: Failed building wheel for fanc
Failed to build fanc
ERROR: Failed to build installable wheels for some pyproject.toml based projects (fanc)