--- a/setup.py
+++ b/setup.py
@@ -499,7 +499,7 @@
     np_include = numpy.get_include()
 
     optimization_level = "O2"
-    if os.name == "posix":
+    if not "MSC" in sys.version:
         default_extra_compile_args = [f"-{optimization_level}"]
         default_libraries = ["m"]
     else: