diff --git a/artiq/coredevice/phaser.py b/artiq/coredevice/phaser.py
index c23fe48e6..ba7a25dd9 100644
--- a/artiq/coredevice/phaser.py
+++ b/artiq/coredevice/phaser.py
@@ -1148,7 +1148,7 @@ class PhaserChannel:
                 b1 >= COEFF_MAX or b1 < -COEFF_MAX):
             raise ValueError("high gains")
 
-        forward_gain = (b0 + b1) * (DATA_MAX - NORM)
+        forward_gain = (b0 + b1) * (1 << SERVO_DATA_WIDTH - 1 - SERVO_COEFF_SHIFT)
         effective_offset = int(round(DATA_MAX * y_offset + forward_gain * x_offset))
 
         self.set_iir_mu(profile, b0, b1, a1, effective_offset)