diff --git a/extensions/roc-plugin-repo/src/actions/lint.js b/extensions/roc-plugin-repo/src/actions/lint.js
index 61cde26..823c2c3 100644
--- a/extensions/roc-plugin-repo/src/actions/lint.js
+++ b/extensions/roc-plugin-repo/src/actions/lint.js
@@ -113,7 +113,7 @@ export default (
                 ...checkstyleXML.checkstyle,
                 file: [
                   ...newXML.checkstyle.file,
-                  ...checkstyleXML.checkstyle.file,
+                  ...(checkstyleXML.checkstyle.file || []),
                 ],
               },
             };