diff --git a/sdks/python/apache_beam/io/iobase.py b/sdks/python/apache_beam/io/iobase.py
index 53215275e050..262eafb118ad 100644
--- a/sdks/python/apache_beam/io/iobase.py
+++ b/sdks/python/apache_beam/io/iobase.py
@@ -1167,7 +1167,7 @@ def expand(self, pcoll):
         AsSingleton(init_result_coll),
         AsIter(write_result_coll),
         min_shards,
-        AsSingleton(pre_finalize_coll)).with_output_types(str)
+        AsSingleton(pre_finalize_coll))
 
 
 class _WriteBundleDoFn(core.DoFn):