diff --git a/pioreactor/background_jobs/stirring.py b/pioreactor/background_jobs/stirring.py
index 4e604301..ce835626 100644
--- a/pioreactor/background_jobs/stirring.py
+++ b/pioreactor/background_jobs/stirring.py
@@ -456,7 +456,8 @@ def set_target_rpm(self, value: float) -> None:
             raise ValueError("Can't set target RPM when no RPM measurement is being made")
 
         self.target_rpm = clamp(0.0, float(value), 5_000.0)
-        self.set_duty_cycle(self.rpm_to_dc_lookup(self.target_rpm))
+        self._estimate_duty_cycle = self.rpm_to_dc_lookup(self.target_rpm)
+        self.set_duty_cycle(self._estimate_duty_cycle)
         self.pid.set_setpoint(self.target_rpm)
 
     def sleep_if_ready(self, seconds):