diff --git a/panc/src/main/scripts/panlint/panlint.py b/panc/src/main/scripts/panlint/panlint.py
index 81e75029..d5327a00 100755
--- a/panc/src/main/scripts/panlint/panlint.py
+++ b/panc/src/main/scripts/panlint/panlint.py
@@ -583,11 +583,11 @@ def lint_file(filename, allow_mvn_templates=False, ignore_components=None, suppr
     components_included = get_components_included(raw_text)
 
     # add ignored components
-    components_included.union(ignore_components)
+    components_included = components_included.union(set(ignore_components))
 
     # Is the current file part of the source tree of a component?
     # If so, regard the component config as being included
-    components_included.union(get_components_from_filename(filename))
+    components_included = components_included.union(get_components_from_filename(filename))
 
     # Start out with no check suppression
     suppressors = set()
diff --git a/panc/src/main/scripts/panlint/tests.py b/panc/src/main/scripts/panlint/tests.py
index c8c71d57..886d0c0a 100755
--- a/panc/src/main/scripts/panlint/tests.py
+++ b/panc/src/main/scripts/panlint/tests.py
@@ -20,7 +20,7 @@
 from sys import argv
 from os.path import basename, dirname, join
 from io import StringIO
-import mock
+from unittest import mock
 import six
 
 import panlint