diff --git a/artiq/test/coredevice/test_rtio.py b/artiq/test/coredevice/test_rtio.py
index 817442dcf..6eaacb390 100644
--- a/artiq/test/coredevice/test_rtio.py
+++ b/artiq/test/coredevice/test_rtio.py
@@ -455,7 +455,10 @@ class RPCTest(ExperimentCase):
         rpc_time_mean = self.dataset_mgr.get("rpc_time_mean")
         print(rpc_time_mean)
         self.assertGreater(rpc_time_mean, 100*ns)
-        self.assertLess(rpc_time_mean, 2*ms)
+        if os.name == 'nt':
+            self.assertLess(rpc_time_mean, 4*ms)
+        else:
+            self.assertLess(rpc_time_mean, 2*ms)
         self.assertLess(self.dataset_mgr.get("rpc_time_stddev"), 1*ms)