diff --git a/src/main/java/eu/dilcis/csip/MetsProfileProcessor.java b/src/main/java/eu/dilcis/csip/MetsProfileProcessor.java
index 4c3ae95..1142c13 100644
--- a/src/main/java/eu/dilcis/csip/MetsProfileProcessor.java
+++ b/src/main/java/eu/dilcis/csip/MetsProfileProcessor.java
@@ -86,8 +86,8 @@ private static void serialisePart(final Part part, final List<Source> sources, f
         writer.flush();
     }
 
-    @Parameters(paramLabel = "FILE", arity = "1..*", description = "A list of METS Profile documents to be processed.")
-    private File[] metsProfiles;
+    @Parameters(paramLabel = "FILE", arity = "0..*", description = "A list of METS Profile documents to be processed.")
+    private File[] metsProfiles = new File[0];
 
     @Option(names = { "-f",
             "--file" }, required = true, paramLabel = "SPECIFICATION", description = "A YAML file that describes the specification structure.")