diff --git a/artiq/test/coredevice/test_rtio.py b/artiq/test/coredevice/test_rtio.py
index e5d225784..d1ca16220 100644
--- a/artiq/test/coredevice/test_rtio.py
+++ b/artiq/test/coredevice/test_rtio.py
@@ -120,7 +120,7 @@ class PulseRateDDS(EnvExperiment):
         dt = seconds_to_mu(5*us)
         while True:
             delay(10*ms)
-            for i in range(100):
+            for i in range(1250):
                 try:
                     with self.core_dds.batch:
                         self.dds0.set(100*MHz)