diff --git a/libraries/AP_HAL_SITL/SITL_Periph_State.h b/libraries/AP_HAL_SITL/SITL_Periph_State.h
index 0aca46d29b..7a9d3ec757 100644
--- a/libraries/AP_HAL_SITL/SITL_Periph_State.h
+++ b/libraries/AP_HAL_SITL/SITL_Periph_State.h
@@ -67,11 +67,11 @@ public:
         "GPS1",
         "none:1",
         "sim:adsb",
-        "none:3",
-        "none:4",
+        "udpclient:127.0.0.1:15550", // for CAN UART test
         "none:5",
         "none:6",
         "none:7",
+        "none:8",
     };
 
     uint8_t get_instance() const { return _instance; }