diff --git a/src/python/grpcio_observability/setup.py b/src/python/grpcio_observability/setup.py
index 78262c7522f78..66a156543b391 100644
--- a/src/python/grpcio_observability/setup.py
+++ b/src/python/grpcio_observability/setup.py
@@ -165,7 +165,7 @@ def get_ext_filename(self, ext_name):
 if EXTRA_ENV_COMPILE_ARGS is None:
     EXTRA_ENV_COMPILE_ARGS = ""
     if "win32" in sys.platform:
-        EXTRA_ENV_COMPILE_ARGS += "/std=c++17"
+        EXTRA_ENV_COMPILE_ARGS += "/std:c++17"
         # We need to statically link the C++ Runtime, only the C runtime is
         # available dynamically
         EXTRA_ENV_COMPILE_ARGS += " /MT"