diff --git a/scripts/Engineering/gui/engineering_diffraction/engineering_diffraction.py b/scripts/Engineering/gui/engineering_diffraction/engineering_diffraction.py
index 6b38972c87c9a5e778220c87f5f00137e1d3d736..5d22268cef13ddf4c19ff241778eb1f4d3aba9ee 100644
--- a/scripts/Engineering/gui/engineering_diffraction/engineering_diffraction.py
+++ b/scripts/Engineering/gui/engineering_diffraction/engineering_diffraction.py
@@ -50,7 +50,7 @@ class EngineeringDiffractionGui(QtWidgets.QMainWindow, Ui_main_window):
         self.lineEdit_RBNumber.textChanged.connect(slot)
 
     def set_on_instrument_changed(self, slot):
-        self.comboBox_instrument.currentTextChanged.connect(slot)
+        self.comboBox_instrument.currentIndexChanged.connect(slot)
 
     def open_help_window(self):
         InterfaceManager().showCustomInterfaceHelp(self.doc)
diff --git a/scripts/Engineering/gui/engineering_diffraction/tabs/calibration/presenter.py b/scripts/Engineering/gui/engineering_diffraction/tabs/calibration/presenter.py
index 5515a5f5c5dcc78e00d1686ae08d099eef8535cf..113ba2e580a42de72cab9117e10ffce5757e3fa1 100644
--- a/scripts/Engineering/gui/engineering_diffraction/tabs/calibration/presenter.py
+++ b/scripts/Engineering/gui/engineering_diffraction/tabs/calibration/presenter.py
@@ -46,6 +46,12 @@ class CalibrationPresenter(object):
         self.disable_calibrate_buttons()
 
     def set_instrument_override(self, instrument):
+        if instrument == 0:
+            instrument = "ENGINX"
+        elif instrument == 1:
+            instrument = "IMAT"
+        else:
+            raise ValueError("Invalid instrument index")
         self.view.set_instrument_override(instrument)
         self.instrument = instrument