diff --git a/phosphor-mapper b/phosphor-mapper
index 25d9867..4303434 100644
--- a/phosphor-mapper
+++ b/phosphor-mapper
@@ -24,10 +24,10 @@
     parser = ArgumentParser()
     parser.add_argument(
         '-p', '--path_namespaces',
-        required=True)
+        default="")
     parser.add_argument(
         '-s', '--service_namespaces',
-        default="")
+        required=True)
     parser.add_argument(
         '-i', '--interface_namespaces',
         required=True)