diff --git a/sw/bootloader/src/sc64.c b/sw/bootloader/src/sc64.c
index 0ccaa89..e9dc38a 100644
--- a/sw/bootloader/src/sc64.c
+++ b/sw/bootloader/src/sc64.c
@@ -123,12 +123,16 @@ static void sc64_cmd_irq_callback (void) {
 
 
 const char *sc64_error_description (sc64_error_t error) {
+    if (error == SC64_OK) {
+        return "No error";
+    }
+
     sc64_error_type_t type = (sc64_error_type_t) ((error >> 24) & 0xFF);
     error &= 0xFFFFFF;
 
     if (type == ERROR_TYPE_CFG) {
         switch ((sc64_cfg_error_t) (error)) {
-            case SC64_OK: return "No error";
+            case CFG_OK: return "No error (CFG)";
             case CFG_ERROR_UNKNOWN_COMMAND: return "Unknown command";
             case CFG_ERROR_INVALID_ARGUMENT: return "Invalid argument";
             case CFG_ERROR_INVALID_ADDRESS: return "Invalid address";
diff --git a/sw/bootloader/src/sc64.h b/sw/bootloader/src/sc64.h
index aef256a..39c3490 100644
--- a/sw/bootloader/src/sc64.h
+++ b/sw/bootloader/src/sc64.h
@@ -7,13 +7,17 @@
 #include <stdint.h>
 
 
+#define SC64_OK (0)
+
+
 typedef enum {
+    ERROR_TYPE_OBSOLETE = 0,
     ERROR_TYPE_CFG = 1,
     ERROR_TYPE_SD_CARD = 2,
 } sc64_error_type_t;
 
 typedef enum {
-    SC64_OK = 0,
+    CFG_OK = 0,
     CFG_ERROR_UNKNOWN_COMMAND = 1,
     CFG_ERROR_INVALID_ARGUMENT = 2,
     CFG_ERROR_INVALID_ADDRESS = 3,