diff --git a/plaso/engine/engine.py b/plaso/engine/engine.py
index 81ee912d0c..9f18bc69ba 100644
--- a/plaso/engine/engine.py
+++ b/plaso/engine/engine.py
@@ -354,7 +354,9 @@ def PreprocessSource(
 
       system_configuration = artifacts.SystemConfigurationArtifact(
           code_page=mediator.code_page, language=mediator.language)
-      system_configuration.environment_variables = (
+      # Ensure environment_variables is a list otherwise serialization will
+      # fail.
+      system_configuration.environment_variables = list(
           mediator.GetEnvironmentVariables())
       system_configuration.hostname = mediator.hostname
       system_configuration.keyboard_layout = mediator.GetValue(
diff --git a/plaso/storage/sqlite/sqlite_file.py b/plaso/storage/sqlite/sqlite_file.py
index 42ea9bc32e..085c7270d0 100644
--- a/plaso/storage/sqlite/sqlite_file.py
+++ b/plaso/storage/sqlite/sqlite_file.py
@@ -241,7 +241,13 @@ def _SerializeAttributeContainer(self, container):
           json_dict['_event_data_stream_identifier'] = (
               event_data_stream_identifier.CopyToString())
 
-      serialized_string = json.dumps(json_dict)
+      try:
+        serialized_string = json.dumps(json_dict)
+      except TypeError as exception:
+        raise IOError((
+            'Unable to serialize attribute container: {0:s} with error: '
+            '{1!s}.').format(container.CONTAINER_TYPE, exception))
+
       if not serialized_string:
         raise IOError('Unable to serialize attribute container: {0:s}.'.format(
             container.CONTAINER_TYPE))