diff --git a/libraries/AP_SerialManager/AP_SerialManager_config.h b/libraries/AP_SerialManager/AP_SerialManager_config.h
index a5a962b40c..7dbf0c16a8 100644
--- a/libraries/AP_SerialManager/AP_SerialManager_config.h
+++ b/libraries/AP_SerialManager/AP_SerialManager_config.h
@@ -53,7 +53,7 @@
 
 
 #ifndef AP_SERIALMANAGER_REGISTER_ENABLED
-#define AP_SERIALMANAGER_REGISTER_ENABLED AP_NETWORKING_ENABLED
+#define AP_SERIALMANAGER_REGISTER_ENABLED BOARD_FLASH_SIZE > 1024 && (AP_NETWORKING_ENABLED || HAL_ENABLE_DRONECAN_DRIVERS)
 #endif
 
 // serial ports registered by AP_Networking will use IDs starting at 21 for the first port