diff --git a/libraries/AP_HAL_SITL/CANSocketIface.cpp b/libraries/AP_HAL_SITL/CANSocketIface.cpp
index 03ca3d2a66..8a48a5aa94 100644
--- a/libraries/AP_HAL_SITL/CANSocketIface.cpp
+++ b/libraries/AP_HAL_SITL/CANSocketIface.cpp
@@ -53,6 +53,8 @@ using namespace HALSITL;
 
 CANIface::CANSocketEventSource CANIface::evt_can_socket[HAL_NUM_CAN_IFACES];
 
+uint8_t CANIface::next_interface;
+
 static can_frame makeSocketCanFrame(const AP_HAL::CANFrame& uavcan_frame)
 {
     can_frame sockcan_frame { uavcan_frame.id& AP_HAL::CANFrame::MaskExtID, uavcan_frame.dlc, { } };
diff --git a/libraries/AP_HAL_SITL/CANSocketIface.h b/libraries/AP_HAL_SITL/CANSocketIface.h
index 34916523b1..bb7cc8201f 100644
--- a/libraries/AP_HAL_SITL/CANSocketIface.h
+++ b/libraries/AP_HAL_SITL/CANSocketIface.h
@@ -62,6 +62,9 @@ public:
       , _max_frames_in_socket_tx_queue(2)
     { }
 
+    static uint8_t next_interface;
+    CANIface() : CANIface(next_interface++) {}
+
     ~CANIface() { }
 
     // Initialise CAN Peripheral