--- setup.py	2024-03-24 02:01:15.000000000 +0800
+++ setup.py	2024-07-16 19:44:11.000000000 +0800
@@ -6,6 +6,7 @@
 
 ON_WINDOWS = platform.system() == 'Windows'
 _comp_args = ["DSHARED=1"]
+_comp_args.append('std=c99')
 sources = ['src/gmpy2.c']
 if os.getenv('CIBUILDWHEEL'):
     include_dirs = [os.path.join(os.path.dirname(__file__), '.local', 'include')]
