diff --git a/setup.py b/setup.py
index e2298ab..c093b16 100755
--- a/setup.py
+++ b/setup.py
@@ -57,7 +57,7 @@ setup(
     extras_require={
 
         # serialization
-        'msgspec': ['msgspec; python_version >= 3.9'],
+        'msgspec': ["msgspec; python_version >= '3.9'"],
 
     },
     tests_require=['pytest'],