diff --git a/artiq/coredevice/ad9910.py b/artiq/coredevice/ad9910.py
index 2ef65ae8e..44cd621a4 100644
--- a/artiq/coredevice/ad9910.py
+++ b/artiq/coredevice/ad9910.py
@@ -588,7 +588,7 @@ class AD9910:
             Suitable for :meth:`write_ram`.
         """
         for i in range(len(ram)):
-            ram[i] = self.amplitude_to_asf(amplitude[i]) << 16
+            ram[i] = self.amplitude_to_asf(amplitude[i]) << 18
 
     @portable(flags={"fast-math"})
     def turns_amplitude_to_ram(self, turns, amplitude, ram):