diff --git a/artiq/coredevice/dds.py b/artiq/coredevice/dds.py
index dbe749e08..e90032b1c 100644
--- a/artiq/coredevice/dds.py
+++ b/artiq/coredevice/dds.py
@@ -134,7 +134,7 @@ class _DDSGeneric:
     def asf_to_amplitude(self, asf):
         """Returns the amplitude corresponding to the given amplitude scale
            factor."""
-        return round(amplitude*0x0fff)
+        return asf/0x0fff
 
     @kernel
     def init(self):