diff --git a/update_version.py b/update_version.py
index 98cb726..6e28df7 100644
--- a/update_version.py
+++ b/update_version.py
@@ -89,7 +89,7 @@ def main() -> int:
 
     # Update pyproject.toml
     if pyproject_path.exists():
-        pattern = r'version = "[^"]+"'
+        pattern = r'(?<!python_)version = "[^"]+"'
         success &= update_file(
             pyproject_path,
             pattern,