diff --git a/sort_known_hosts.py b/sort_known_hosts.py
index 192bc32..509fc74 100755
--- a/sort_known_hosts.py
+++ b/sort_known_hosts.py
@@ -90,7 +90,13 @@ if __name__ == '__main__':
     parser = argparse.ArgumentParser(
         formatter_class=argparse.ArgumentDefaultsHelpFormatter
     )
-    parser.add_argument('known_hosts', type=Path, help='known_hosts file to read')
+    parser.add_argument(
+        '-i',
+        '--known_hosts',
+        type=Path,
+        default=f"{os.path.expanduser('~')}/.ssh/known_hosts",
+        help='known_hosts file to read',
+    )
     parser.add_argument('-o', '--output', type=Path, help='output file to write')
     parser.set_defaults(func=main)
     args = parser.parse_args()