diff --git a/src/gui_qt/fit/fitwindow.py b/src/gui_qt/fit/fitwindow.py
index b93ebec..9888685 100644
--- a/src/gui_qt/fit/fitwindow.py
+++ b/src/gui_qt/fit/fitwindow.py
@@ -11,6 +11,7 @@ from pyqtgraph import mkPen
 from nmreval.fit._meta import MultiModel, ModelFactory
 from nmreval.fit.data import Data
 from nmreval.fit.model import Model
+from nmreval.fit.parameter import Parameters
 from nmreval.fit.result import FitResult
 
 from .fit_forms import FitTableWidget
@@ -419,25 +420,37 @@ class QFitDialog(QtWidgets.QWidget, Ui_FitDialog):
     def make_previews(self, x, models_parameters: dict):
         self.preview_lines = []
 
+        # needed to create namespace
+        param_dict = Parameters()
+
+        cnt = 0
+        for model in models_parameters.values():
+            f = model['func']
+            for parameter_list in model['data_parameter'].values():
+                for i, p_value in enumerate(parameter_list[0]):
+                    p_value.name = f.params[i]
+                    param_dict.add_parameter(f'a{cnt}', p_value)
+                    cnt += 1
+
         for k, model in models_parameters.items():
-            f = Model(model['func'])
+            f = model['func']
             is_complex = self._complex[k]
 
             parameters = model['data_parameter']
             color = model['color']
 
             for p, kwargs in parameters.values():
-                print(pp.value for pp in p)
+                p_value = [pp.value for pp in p]
 
                 if is_complex is not None:
-                    y = f.func(x, *p, complex_mode=is_complex, **kwargs)
+                    y = f.func(x, *p_value, complex_mode=is_complex, **kwargs)
                     if np.iscomplexobj(y):
                         self.preview_lines.append(PlotItem(x=x, y=y.real, pen=mkPen(width=3)))
                         self.preview_lines.append(PlotItem(x=x, y=y.imag, pen=mkPen(width=3)))
                     else:
                         self.preview_lines.append(PlotItem(x=x, y=y, pen=mkPen(width=3)))
                 else:
-                    y = f.func(x, *p, **kwargs)
+                    y = f.func(x, *p_value, **kwargs)
                     self.preview_lines.append(PlotItem(x=x, y=y, pen=mkPen(width=3)))
 
                 if isinstance(f, MultiModel):
@@ -445,7 +458,7 @@ class QFitDialog(QtWidgets.QWidget, Ui_FitDialog):
                     if is_complex is not None:
                         sub_kwargs.update({'complex_mode': is_complex})
 
-                    for i, s in enumerate(f.subs(x, *p, **sub_kwargs)):
+                    for i, s in enumerate(f.subs(x, *p_value, **sub_kwargs)):
                         pen_i = mkPen(QtGui.QColor.fromRgbF(*color[i]))
                         if np.iscomplexobj(s):
                             self.preview_lines.append(PlotItem(x=x, y=s.real, pen=pen_i))
@@ -453,6 +466,8 @@ class QFitDialog(QtWidgets.QWidget, Ui_FitDialog):
                         else:
                             self.preview_lines.append(PlotItem(x=x, y=s, pen=pen_i))
 
+        param_dict.clear()
+
         return self.preview_lines
 
     def set_parameter(self, parameter: dict[str, FitResult]):