diff --git a/artiq/coredevice/urukul.py b/artiq/coredevice/urukul.py
index 2cc0b80ba..d8dc058db 100644
--- a/artiq/coredevice/urukul.py
+++ b/artiq/coredevice/urukul.py
@@ -24,7 +24,7 @@ CFG_RF_SW = 0
 CFG_LED = 4
 CFG_PROFILE = 8
 CFG_IO_UPDATE = 12
-CFG_MASK_NU = 16
+CFG_MASK_NU = 13
 CFG_CLK_SEL = 17
 CFG_SYNC_SEL = 18
 CFG_RST = 19