diff --git a/artiq/test/coredevice/test_rtio.py b/artiq/test/coredevice/test_rtio.py
index 4069e046a..401f4109b 100644
--- a/artiq/test/coredevice/test_rtio.py
+++ b/artiq/test/coredevice/test_rtio.py
@@ -92,7 +92,7 @@ class ClockGeneratorLoopback(EnvExperiment):
         self.core.reset()
         self.loop_clock_in.input()
         self.loop_clock_out.stop()
-        delay(20*us)
+        delay(200*us)
         with parallel:
             self.loop_clock_in.gate_rising(10*us)
             with sequential: