diff --git a/src/fido/otp.c b/src/fido/otp.c
index 9b31027..52f1f8b 100644
--- a/src/fido/otp.c
+++ b/src/fido/otp.c
@@ -270,10 +270,11 @@ int otp_button_pressed(uint8_t slot) {
         }
     }
     else if (otp_config->cfg_flags & SHORT_TICKET || otp_config->cfg_flags & STATIC_TICKET) {
+        uint8_t fixed_size = FIXED_SIZE + UID_SIZE + KEY_SIZE;
         if (otp_config->cfg_flags & SHORT_TICKET) {
-            otp_config->fixed_size /= 2;
+            fixed_size /= 2;
         }
-        add_keyboard_buffer(otp_config->fixed_data, otp_config->fixed_size, false);
+        add_keyboard_buffer(otp_config->fixed_data, fixed_size, false);
         if (otp_config->tkt_flags & APPEND_CR) {
             append_keyboard_buffer((const uint8_t *) "\x28", 1);
         }