diff --git a/artiq/frontend/lda_controller.py b/artiq/frontend/lda_controller.py
index 0f3a0ab32..5753af44e 100755
--- a/artiq/frontend/lda_controller.py
+++ b/artiq/frontend/lda_controller.py
@@ -18,8 +18,9 @@ def get_argparser():
                         help="USB serial number of the device. "
                              "The serial number is written on a sticker under "
                              "the device, you should write for example "
-                             "-d \"SN:03461\". You must prepend enough 0 for it "
-                             "to be 5 digits.")
+                             "-d \"SN:03461\". You must prepend enough 0 for "
+                             "it to be 5 digits. If omitted, the first "
+                             "available device will be used.")
     parser.add_argument("--simulation", action="store_true",
                         help="Put the driver in simulation mode.")
     verbosity_args(parser)