Index: setup.py
--- setup.py.orig
+++ setup.py
@@ -42,7 +42,6 @@ source_ext = ".pyx" if cythonize else ".c"
 ext_modules = [
     Extension(
         "rencode._rencode",
-        extra_compile_args=["-O3"],
         sources=["rencode/_rencode" + source_ext],
     ),
 ]
