diff --git a/artiq/sim/devices.py b/artiq/sim/devices.py
index 41b7b59c5..3e2295bf6 100644
--- a/artiq/sim/devices.py
+++ b/artiq/sim/devices.py
@@ -1,7 +1,7 @@
 from random import Random
 import numpy
 
-from artiq.language.core import delay, at_mu, kernel
+from artiq.language.core import kernel
 from artiq.sim import time
 
 
diff --git a/artiq/sim/time.py b/artiq/sim/time.py
index 72cd3313f..676966735 100644
--- a/artiq/sim/time.py
+++ b/artiq/sim/time.py
@@ -70,4 +70,4 @@ class Manager:
         return r
 
 manager = Manager()
-core_language.set_time_manager(manager)
+# NAC3TODO core_language.set_time_manager(manager)