diff --git a/src/gui_qt/fit/fit_parameter.py b/src/gui_qt/fit/fit_parameter.py
index 30b4b31..d0924a8 100644
--- a/src/gui_qt/fit/fit_parameter.py
+++ b/src/gui_qt/fit/fit_parameter.py
@@ -243,7 +243,7 @@ class QFitParameterWidget(QtWidgets.QWidget, Ui_FormFit):
                     else:
                         lb, ub = bds[i]
                         try:
-                            if not (lb < p_i < ub):
+                            if not ((lb < p_i < ub) or (not is_fixed[i])):
                                 raise ValueError(f'Parameter {g.name} is outside bounds ({lb}, {ub})')
                         except TypeError:
                             pass
diff --git a/src/nmreval/fit/parameter.py b/src/nmreval/fit/parameter.py
index 2aaeb0b..65a320b 100644
--- a/src/nmreval/fit/parameter.py
+++ b/src/nmreval/fit/parameter.py
@@ -222,7 +222,7 @@ class Parameter:
             self.var = False
         else:
             if isinstance(self.lb, (int, float)) and isinstance(self.ub, (int, float)):
-                if self.lb <= value <= self.ub:
+                if (self.lb <= value <= self.ub) or (not self.var):
                     self._value = value
                 else:
                     raise ValueError('Value of parameter is outside bounds')