diff --git a/pytec/tec_qt.py b/pytec/tec_qt.py
index 857a18f..2b86f6b 100644
--- a/pytec/tec_qt.py
+++ b/pytec/tec_qt.py
@@ -156,8 +156,8 @@ class ChannelGraphs:
         self._i_plot = LiveLinePlot(name='Measured')
         self._iset_plot = LiveLinePlot(name='Set', pen=pg.mkPen('r'))
 
-        self.t_line = self._t_widget.getPlotItem().addLine(label='{value} °C')
-        self.t_line.setVisible(False)
+        self._t_line = self._t_widget.getPlotItem().addLine(label='{value} °C')
+        self._t_line.setVisible(False)
 
         for graph in t_widget, i_widget:
             time_axis = LiveAxis('bottom', text="Time since Thermostat reset", **{Axis.TICK_FORMAT: Axis.DURATION})
@@ -203,6 +203,17 @@ class ChannelGraphs:
         for connector in self.t_connector, self.i_connector, self.iset_connector:
             connector.clear()
 
+    def set_t_line(self, temp=None, visible=None):
+        if visible is not None:
+            self._t_line.setVisible(visible)
+        if temp is not None:
+            self._t_line.setValue(temp)
+            if visible is False:
+                # PyQtGraph does not update this text when the line
+                # is not visible, but we need it so that the temperature
+                # label doesn't display 0 °C despite not being at 0 °C.
+                self._t_line.label.setText(f"{temp} °C")
+
 
 class MainWindow(QtWidgets.QMainWindow, Ui_MainWindow):
 
@@ -809,7 +820,7 @@ class MainWindow(QtWidgets.QMainWindow, Ui_MainWindow):
                 self.params[channel].child("PID Config", "Max Current Output").setValue(settings["parameters"]["output_max"] * 1000)
                 self.params[channel].child("PID Config", "Min Current Output").setValue(settings["parameters"]["output_min"] * 1000)
                 self.params[channel].child("Output Config", "Control Method", "Set Temperature").setValue(settings["target"])
-                self.channel_graphs[channel].t_line.setValue(round(settings["target"], 6))
+                self.channel_graphs[channel].set_t_line(temp=round(settings["target"], 6))
 
     @pyqtSlot(list)
     def update_report(self, report_data):
@@ -818,7 +829,7 @@ class MainWindow(QtWidgets.QMainWindow, Ui_MainWindow):
             self.channel_graphs[channel].plot_append(settings)
             with QSignalBlocker(self.params[channel]):
                 self.params[channel].child("Output Config", "Control Method").setValue("Temperature PID" if settings["pid_engaged"] else "Constant Current")
-                self.channel_graphs[channel].t_line.setVisible(settings["pid_engaged"])
+                self.channel_graphs[channel].set_t_line(visible=settings['pid_engaged'])
                 self.params[channel].child("Output Config", "Control Method", "Set Current").setValue(settings["i_set"] * 1000)
                 if settings['temperature'] is not None and settings['tec_i'] is not None:
                     self.params[channel].child("Temperature").setValue(settings['temperature'])