diff --git a/examples/PingTest_V1.no-batch.openapi3.json b/examples/PingTest_V1.no-batch.openapi3.json
index d6c10ab9..fa65cbeb 100644
--- a/examples/PingTest_V1.no-batch.openapi3.json
+++ b/examples/PingTest_V1.no-batch.openapi3.json
@@ -255,4 +255,4 @@
             }
         }
     }
-}
+}
\ No newline at end of file
diff --git a/lib/cli.js b/lib/cli.js
index 23267b77..a4deb87d 100755
--- a/lib/cli.js
+++ b/lib/cli.js
@@ -101,7 +101,7 @@ function convert(source) {
     skipBatchPath: argv.skipBatchPath,
     defaultTitle: argv.title,
     defaultDescription: argv.description,
-    rootResourcesToKeep: Array.isArray(argv.keep) ? argv.keep : [argv.keep],
+    rootResourcesToKeep: Array.isArray(argv.keep) ? argv.keep : argv.keep? [argv.keep]: undefined,
   });
 
   stringifyStream(openapi, null, argv.pretty ? 4 : 0).pipe(
diff --git a/package.json b/package.json
index 8878ea55..746012f7 100644
--- a/package.json
+++ b/package.json
@@ -35,6 +35,7 @@
   },
   "scripts": {
     "build": "node lib/transform.js",
+    "pretest": "node lib/cli.js -p --skipBatchPath -t examples/PingTest_V1.no-batch.openapi3.json examples/PingTest_V1.xml",
     "test": "c8 mocha",
     "watch": "mocha --watch"
   },