diff --git a/lib/galaxy/jobs/actions/post.py b/lib/galaxy/jobs/actions/post.py
index fdfc4cd92dd..02e9b527897 100644
--- a/lib/galaxy/jobs/actions/post.py
+++ b/lib/galaxy/jobs/actions/post.py
@@ -74,6 +74,10 @@ class ChangeDatatypeAction(DefaultJobAction):
         for dataset_assoc in job.output_datasets:
             if action.output_name == '' or dataset_assoc.name == action.output_name:
                 app.datatypes_registry.change_datatype(dataset_assoc.dataset, action.action_arguments['newtype'])
+        for dataset_collection_assoc in job.output_dataset_collection_instances:
+            if action.output_name == '' or dataset_collection_assoc.name == action.output_name:
+                for dataset_instance in dataset_collection_assoc.dataset_collection_instance.dataset_instances:
+                    app.datatypes_registry.change_datatype(dataset_instance, action.action_arguments['newtype'])
 
     @classmethod
     def get_short_str(cls, pja):