diff --git a/artiq/test/coredevice/test_rtio.py b/artiq/test/coredevice/test_rtio.py
index 6e7e50365..c968bb37e 100644
--- a/artiq/test/coredevice/test_rtio.py
+++ b/artiq/test/coredevice/test_rtio.py
@@ -362,7 +362,7 @@ class CoredeviceTest(ExperimentCase):
         rtt = self.dataset_mgr.get("rtt")
         print(rtt)
         self.assertGreater(rtt, 0*ns)
-        self.assertLess(rtt, 124*ns)
+        self.assertLess(rtt, 140*ns)
 
     def test_clock_generator_loopback(self):
         self.execute(ClockGeneratorLoopback)