diff --git a/postgrest/base_request_builder.py b/postgrest/base_request_builder.py
index eb7721e2..b86d8f29 100644
--- a/postgrest/base_request_builder.py
+++ b/postgrest/base_request_builder.py
@@ -405,7 +405,7 @@ def ilike(self: Self, column: str, pattern: str) -> Self:
         """
         return self.filter(column, Filters.ILIKE, pattern)
 
-    def or_(self: Self, filters: str, reference_table: Union[str, None] = None) -> Self:
+    def or_(self: Self, filters: str, reference_table: Optional[str] = None) -> Self:
         """An 'or' filter
 
         Args: