diff --git a/src/gui_qt/fit/fit_forms.py b/src/gui_qt/fit/fit_forms.py
index 6f2a424..624b13d 100644
--- a/src/gui_qt/fit/fit_forms.py
+++ b/src/gui_qt/fit/fit_forms.py
@@ -10,6 +10,10 @@ from ..lib.tables import TableWidget
 
 
 class FitModelWidget(QtWidgets.QWidget, Ui_FitParameter):
+    """
+    Widget to show a global parameter
+    """
+
     value_requested = QtCore.pyqtSignal(object)
     value_changed = QtCore.pyqtSignal(str)
     state_changed = QtCore.pyqtSignal()
@@ -73,11 +77,9 @@ class FitModelWidget(QtWidgets.QWidget, Ui_FitParameter):
         if bds is not None:
             self.set_bounds(*bds)
 
-        if fixed is not None:
-            self.fixed_check.setCheckState(QtCore.Qt.Unchecked if fixed else QtCore.Qt.Checked)
+        self.fixed_check.setCheckState(QtCore.Qt.CheckState.Unchecked if fixed else QtCore.Qt.CheckState.Checked)
 
-        if glob is not None:
-            self.global_checkbox.setCheckState(QtCore.Qt.Checked if glob else QtCore.Qt.Unchecked)
+        self.global_checkbox.setCheckState(QtCore.Qt.CheckState.Checked if glob else QtCore.Qt.CheckState.Unchecked)
 
     def get_parameter(self):
         try:
@@ -126,7 +128,7 @@ class FitModelWidget(QtWidgets.QWidget, Ui_FitParameter):
             is_text = True
             self.global_checkbox.setCheckState(False)
 
-        self.set_fixed(is_text)
+        self.set_fixed(is_text or self.fixed_check.isChecked())
 
 
 class QSaveModelDialog(QtWidgets.QDialog, Ui_SaveDialog):