diff --git a/artiq/coredevice/core.py b/artiq/coredevice/core.py
index ecd18a429..15bb80a5d 100644
--- a/artiq/coredevice/core.py
+++ b/artiq/coredevice/core.py
@@ -4,6 +4,7 @@ from numpy import int32, int64
 import nac3artiq
 
 from artiq.language.core import *
+from artiq.language.core import _ConstGenericMarker  # nac3artiq.NAC3 needs to look up this private class
 from artiq.language import core as core_language
 from artiq.language.units import *
 from artiq.language.embedding_map import EmbeddingMap