diff --git a/invenio_communities/communities/schema.py b/invenio_communities/communities/schema.py
index 606637221..db4cd201e 100644
--- a/invenio_communities/communities/schema.py
+++ b/invenio_communities/communities/schema.py
@@ -88,9 +88,11 @@ def clean(self, data, **kwargs):
         Why: We want to allow the output of a Schema dump, to be a valid input
              to a Schema load without causing strange issues.
         """
-        for name, field in self.fields.items():
-            if field.dump_only:
-                data.pop(name, None)
+        value_is_dict = isinstance(data, dict)
+        if value_is_dict:
+            for name, field in self.fields.items():
+                if field.dump_only:
+                    data.pop(name, None)
         return data