diff --git a/isisd/isis_misc.c b/isisd/isis_misc.c
index 25f7f8609b..27d06e8da7 100644
--- a/isisd/isis_misc.c
+++ b/isisd/isis_misc.c
@@ -538,6 +538,26 @@ void log_multiline(int priority, const char *prefix, const char *format, ...)
 		XFREE(MTYPE_TMP, p);
 }
 
+char *log_uptime(time_t uptime, char *buf, size_t nbuf)
+{
+	struct tm *tm;
+	time_t difftime = time(NULL);
+	difftime -= uptime;
+	tm = gmtime(&difftime);
+
+	if (difftime < ONE_DAY_SECOND)
+		snprintf(buf, nbuf, "%02d:%02d:%02d", tm->tm_hour, tm->tm_min,
+			 tm->tm_sec);
+	else if (difftime < ONE_WEEK_SECOND)
+		snprintf(buf, nbuf, "%dd%02dh%02dm", tm->tm_yday, tm->tm_hour,
+			 tm->tm_min);
+	else
+		snprintf(buf, nbuf, "%02dw%dd%02dh", tm->tm_yday / 7,
+			 tm->tm_yday - ((tm->tm_yday / 7) * 7), tm->tm_hour);
+
+	return buf;
+}
+
 void vty_multiline(struct vty *vty, const char *prefix, const char *format, ...)
 {
 	char shortbuf[256];
diff --git a/isisd/isis_misc.h b/isisd/isis_misc.h
index fbfabaf24f..5cdbbfb058 100644
--- a/isisd/isis_misc.h
+++ b/isisd/isis_misc.h
@@ -80,6 +80,7 @@ enum { ISIS_UI_LEVEL_BRIEF,
 #include "lib/log.h"
 void log_multiline(int priority, const char *prefix, const char *format, ...)
 	PRINTFRR(3, 4);
+char *log_uptime(time_t uptime, char *buf, size_t nbuf);
 struct vty;
 void vty_multiline(struct vty *vty, const char *prefix, const char *format, ...)
 	PRINTFRR(3, 4);