diff --git a/artiq/coredevice/urukul.py b/artiq/coredevice/urukul.py
index b37590e1a..6605d852b 100644
--- a/artiq/coredevice/urukul.py
+++ b/artiq/coredevice/urukul.py
@@ -14,7 +14,8 @@ SPI_CONFIG = (0*spi.SPI_OFFLINE | 0*spi.SPI_END |
 # SPI clock write and read dividers
 SPIT_CFG_WR = 2
 SPIT_CFG_RD = 16
-SPIT_ATT_WR = 2
+# 30 MHz fmax, 20 ns setup, 40 ns shift to latch (limiting)
+SPIT_ATT_WR = 6
 SPIT_ATT_RD = 16
 SPIT_DDS_WR = 2
 SPIT_DDS_RD = 16