diff --git a/build/gen.py b/build/gen.py
index 6f3652ee..eface2bd 100755
--- a/build/gen.py
+++ b/build/gen.py
@@ -235,8 +235,8 @@ def is_gcc(cxx):
       f'{cxx} -dM -E -',
       shell=True,
       stdin=subprocess.DEVNULL,
-      text=True,
-      capture_output=True)
+      stdout=subprocess.PIPE,
+      universal_newlines=True)
 
   return ret.returncode == 0 and "#define __GNUC__" in ret.stdout and not "#define __clang__" in ret.stdout