diff --git a/src/utils/os.h b/src/utils/os.h
index 07abf7a9a..1bbaea3a4 100644
--- a/src/utils/os.h
+++ b/src/utils/os.h
@@ -108,6 +108,26 @@ static inline int os_reltime_expired(struct os_reltime *now,
 }
 
 
+static inline void os_reltime_add_ms(struct os_reltime *ts, int ms)
+{
+	ts->usec += ms * 1000;
+	while (ts->usec >= 1000000) {
+		ts->sec++;
+		ts->usec -= 1000000;
+	}
+	while (ts->usec < 0) {
+		ts->sec--;
+		ts->usec += 1000000;
+	}
+}
+
+
+static inline int os_reltime_in_ms(struct os_reltime *ts)
+{
+	return ts->sec * 1000 + ts->usec / 1000;
+}
+
+
 static inline int os_reltime_initialized(struct os_reltime *t)
 {
 	return t->sec != 0 || t->usec != 0;