--- meson.build
+++ meson.build
@@ -29,6 +29,7 @@ warning_c_args = [
 ]
 
 extra_c_args = [
+  '-D_DARWIN_C_SOURCE',
   '-fno-strict-aliasing',
   '-fno-delete-null-pointer-checks',
   '-fdiagnostics-show-option',