diff --git a/brewpi/brewpi.py b/brewpi/brewpi.py
index 533c028..9996fd2 100755
--- a/brewpi/brewpi.py
+++ b/brewpi/brewpi.py
@@ -74,7 +74,7 @@ if __name__ == '__main__':
 	sud_path = config.get('sud')
 	if sud_path:
 		sud = Sud(sud_path)
-		taskmgr.add(SudTask(sud, tc, stirrer, DT_TASK, dispatcher.msgio_get("Sud")))
+		taskmgr.add(SudTask(sud, tc, stirrer, pot, DT_TASK, dispatcher.msgio_get("Sud")))
 
 	# Tracer
 	taskmgr.add(TracerTask(sensor, heater, tc, trace_tc, DT_TASK_TRACER, dispatcher.msgio_get("Tracer")))
diff --git a/tasks/sud.py b/tasks/sud.py
index d879359..3f91ba7 100644
--- a/tasks/sud.py
+++ b/tasks/sud.py
@@ -3,6 +3,7 @@ from tasks import ATask
 from ws.message import MsgIo
 from utils.value import ChangedFloat
 from components import APid, AStirrer
+from components.plant import APlant
 from components.sud import Sud, SudState
 
 # How close theta_ist needs to be to theta_soll_set to count as "reached".
@@ -10,14 +11,25 @@ TEMP_REACHED_TOLERANCE = 0.2
 
 
 class SudTask(ATask):
-	def __init__(self, sud: Sud, tc: APid, stirrer: AStirrer, interval, msg_handler: MsgIo):
+	def __init__(self, sud: Sud, tc: APid, stirrer: AStirrer, pot: APlant, interval, msg_handler: MsgIo):
 		ATask.__init__(self, interval)
 		self.sud = sud
 		self.tc = tc
 		self.stirrer = stirrer
+		self.pot = pot
 		self.msg_handler = msg_handler
 		msg_handler.set_recv_handler(self.recv)
 
+	def apply_plant_params(self, step):
+		"""Keeps the real plant's and the controller's internal model's
+		lumped (M, C) in sync with the step's grain_mass/water_mass, since
+		those vary over the course of a brew (malt going in, water boiling
+		off) - mirrors demo_sud.py's apply_plant_params()."""
+		params = self.sud.derive_plant_params(step.get('grain_mass', 0), step.get('water_mass', 0))
+		self.pot.set_thermal_params(params['M'], params['C'])
+		if hasattr(self.tc, 'set_model_params'):
+			self.tc.set_model_params(params['M'], params['C'])
+
 	def apply_stirrer(self, step):
 		stirrer_cfg = step.get('ramp', step.get('hold', {})).get('stirrer', {})
 		speed = stirrer_cfg.get('speed', 0)
@@ -35,6 +47,7 @@ class SudTask(ATask):
 		ramp = step.get('ramp') if step else None
 		hold = step.get('hold') if step else None
 		if step is not None:
+			self.apply_plant_params(step)
 			if ramp is not None:
 				self.tc.set_theta_soll(ramp['temp'])
 				self.tc.set_heatrate_soll(ramp['rate'])