diff --git a/components/utilities/ulog/ulog.c b/components/utilities/ulog/ulog.c
index 04a36a70aa..ab22e516a5 100644
--- a/components/utilities/ulog/ulog.c
+++ b/components/utilities/ulog/ulog.c
@@ -274,7 +274,6 @@ RT_WEAK rt_size_t ulog_formater(char *log_buf, rt_uint32_t level, const char *ta
     /* add time info */
     {
 #ifdef ULOG_TIME_USING_TIMESTAMP
-        extern struct tm* localtime_r(const time_t* t, struct tm* r);
         static struct timeval now;
         static struct tm *tm, tm_tmp;
         static rt_bool_t check_usec_support = RT_FALSE, usec_is_support = RT_FALSE;