diff --git a/mailman_sync.py b/mailman_sync.py
index 7a52d59..9388468 100755
--- a/mailman_sync.py
+++ b/mailman_sync.py
@@ -176,10 +176,14 @@ def parse_arguments():
         help="Path to Mailman site admin scripts (default %(default)s)",
     )
     argp.add_argument("--api", required=True, help="API endpoint to retrieve JSON from")
-    argp.add_argument("--list-suffix", help="Suffix for mailing lists")
-    argp.add_argument("--urlhost", help="Urlhost to use when creating new lists")
+    argp.add_argument("--list-suffix", help="Suffix for mailing lists", default="")
     argp.add_argument(
-        "--admin", help="Admin email address to use when creating new lists"
+        "--urlhost", help="Urlhost to use when creating new lists", required=True
+    )
+    argp.add_argument(
+        "--admin",
+        help="Admin email address to use when creating new lists",
+        required=True,
     )
     argp.add_argument(
         "-n",