diff --git a/third_party/bigframes_vendored/pandas/core/series.py b/third_party/bigframes_vendored/pandas/core/series.py
index e6af1648fd..48bcca4ad8 100644
--- a/third_party/bigframes_vendored/pandas/core/series.py
+++ b/third_party/bigframes_vendored/pandas/core/series.py
@@ -677,13 +677,13 @@ def __matmul__(self, other):
         """
         Matrix multiplication using binary `@` operator in Python>=3.5.
         """
-        raise NotImplementedError(constants.ABSTRACT_METHOD_ERROR_MESSAGE)
+        return NotImplemented
 
     def __rmatmul__(self, other):
         """
         Matrix multiplication using binary `@` operator in Python>=3.5.
         """
-        raise NotImplementedError(constants.ABSTRACT_METHOD_ERROR_MESSAGE)
+        return NotImplemented
 
     def sort_values(
         self,