diff --git a/api/apibasic/reg_index.cpp b/api/apibasic/reg_index.cpp
index f84ac02..a278549 100644
--- a/api/apibasic/reg_index.cpp
+++ b/api/apibasic/reg_index.cpp
@@ -121,7 +121,7 @@ static reginfo_t table[] = {
     REG_ITERM(kreg_id_card_reader_is_online),
 };
 
-reginfo_t *get_reginfo_by_index(uint32_t index) {
+reginfo_t *get_reginfo_by_index(int32_t index) {
   for (int i = 0; i < sizeof(table) / sizeof(table[0]); i++) {
     if (table[i].index == index) {
       return &table[i];
@@ -130,7 +130,7 @@ reginfo_t *get_reginfo_by_index(uint32_t index) {
   return nullptr;
 }
 
-const char *regindex2str(uint32_t index) {
+const char *regindex2str(int32_t index) {
   for (int i = 0; i < sizeof(table) / sizeof(table[0]); i++) {
     if (table[i].index == index) {
       return table[i].regname;