diff --git a/mastodon_blocklist_deploy/cli.py b/mastodon_blocklist_deploy/cli.py
index 31946d0..29bfb24 100644
--- a/mastodon_blocklist_deploy/cli.py
+++ b/mastodon_blocklist_deploy/cli.py
@@ -78,7 +78,7 @@ def cli():
     parser.add_argument('-o', '--output', help="Filename where to export the blocklist")
     parser.add_argument('-v', '--verbose', action='store_true')
     parser.add_argument('-n', '--no-delete', action='store_true', help="Do not delete existing blocks")
-    parser.add_argument('--format', help="Export format: toml|markdown|csv|json")
+    parser.add_argument('--format', default="toml", type=str, help="Export format: toml|markdown|csv|json")
     parser.add_argument('--private', action='store_true', help="When the flag is set, private comment will also be "
                                                                "exported.")
     args = parser.parse_args()