diff --git a/USB-protocol.md b/USB-protocol.md
index a1e13c4..7927d09 100644
--- a/USB-protocol.md
+++ b/USB-protocol.md
@@ -119,7 +119,7 @@ Commands are typically a one-byte command ID, followed by a variable amount of d
     * **`0x01`: Start capture/wait for trigger**
       * Response:
         * 3-byte "trigger instant" (little-endian): this is the point at which the trigger happened, units are `MS1*16`. (That is, if the trigger happened at the very last sample, this value will be `MS1*16`. If it happens right in the middle, it'll be 50% of `MS1*16`.) (For `MS1`: see settings blob.)
-        * 1 status byte
+        * 1 status byte: `0xdd` indicates success, no other values seen.
     * **`0x02`: Start generating an uploaded signal indefinitely**
     * **`0x03`: Start capture/generate/wait for trigger in mixed mode**
       * Response: same as `0xf0 0x01`