diff --git a/caom2/caom2/obs_reader_writer.py b/caom2/caom2/obs_reader_writer.py
index 7341f393..fc09e920 100644
--- a/caom2/caom2/obs_reader_writer.py
+++ b/caom2/caom2/obs_reader_writer.py
@@ -261,8 +261,9 @@ def _add_keywords(self, keywords_list, element, ns, required):
                     keywords_list.add(keyword)
         else:
             keywords_element = self._get_child_element("keywords", element, ns, required)
-            for keyword in keywords_element.iterchildren(tag=("{" + ns + "}keyword")):
-                keywords_list.add(keyword.text)
+            if keywords_element is not None:
+                for keyword in keywords_element.iterchildren(tag=("{" + ns + "}keyword")):
+                    keywords_list.add(keyword.text)
 
 
     def _get_algorithm(self, element_tag, parent, ns, required):
diff --git a/caom2/setup.cfg b/caom2/setup.cfg
index 87a0efd5..34be1d5a 100644
--- a/caom2/setup.cfg
+++ b/caom2/setup.cfg
@@ -39,7 +39,7 @@ edit_on_github = False
 github_project = opencadc/caom2tools
 install_requires = future lxml aenum
 # version should be PEP386 compatible (http://www.python.org/dev/peps/pep-0386)
-version = 2.3.0a3
+version = 2.3.0a4
 
 
 [entry_points]