1 files changed, 1 insertions, 0 deletions

diff --git a/PROTOCOL.u2f b/PROTOCOL.u2f
index fd0cd0de0..58f75ba28 100644
--- a/PROTOCOL.u2f
+++ b/PROTOCOL.u2f
@@ -249,6 +249,7 @@ The middleware library need only expose a handful of functions:
         #define SSH_SK_ERR_GENERAL              -1
         #define SSH_SK_ERR_UNSUPPORTED          -2
         #define SSH_SK_ERR_PIN_REQUIRED         -3
+        #define SSH_SK_ERR_DEVICE_NOT_FOUND     -4
 
         struct sk_enroll_response {
                 uint8_t *public_key;