diff --git a/source/libs/function/src/udfd.c b/source/libs/function/src/udfd.c
index 8ff0dc15a56068d466664df01f4f2291100741f2..14e358ea005c161b9281a0d8c14530f7cf600b79 100644
--- a/source/libs/function/src/udfd.c
+++ b/source/libs/function/src/udfd.c
@@ -959,8 +959,8 @@ int32_t udfdInitResidentFuncs() {
   char* pSave = tsUdfdResFuncs;
   char* token;
   while ((token = strtok_r(pSave, ",", &pSave)) != NULL) {
-    char func[TSDB_FUNC_NAME_LEN] = {0};
-    strncpy(func, token, sizeof(func));
+    char func[TSDB_FUNC_NAME_LEN+1] = {0};
+    strncpy(func, token, TSDB_FUNC_NAME_LEN);
     taosArrayPush(global.residentFuncs, func);
   }