diff --git a/wasp/drivers/nrf_rtc.py b/wasp/drivers/nrf_rtc.py
index 54c58f1..d907461 100644
--- a/wasp/drivers/nrf_rtc.py
+++ b/wasp/drivers/nrf_rtc.py
@@ -57,3 +57,7 @@ class RTC(object):
     def get_time(self):
         localtime = self.get_localtime()
         return localtime[3:6]
+
+    def get_uptime_ms(self):
+        """Return the current uptime in milliseconds."""
+        return self.uptime * 1000