diff --git a/src/nmreval/fit/result.py b/src/nmreval/fit/result.py
index d77fd88..bd954b4 100644
--- a/src/nmreval/fit/result.py
+++ b/src/nmreval/fit/result.py
@@ -401,7 +401,10 @@ class FitResult(Points):
             raise ValueError('no fit function available to calculate new y values')
 
         new_fit = self.copy()
-        y_values = self.func.func(self.p_final, x_values, **self.fun_kwargs)
+        fun_kwargs = {k: v for k, v in self.fun_kwargs.items()}
+        if self.fun_kwargs.get('complex_mode', -1) == -1:
+            fun_kwargs.pop('complex_mode', None)
+        y_values = self.func.func(self.p_final, x_values, **fun_kwargs)
         y_values = check_complex(y_values, self.fun_kwargs.get('complex_mode', -1), self._data_complex)
 
         new_fit.set_data(x_values, y_values, y_err=0.0)
@@ -414,6 +417,9 @@ class FitResult(Points):
 
         part_functions = []
         actual_mode = self.fun_kwargs.get('complex_mode', -1)
+        fun_kwargs = {k: v for k, v in self.fun_kwargs.items()}
+        if self.fun_kwargs.get('complex_mode', -1) == -1:
+            fun_kwargs.pop('complex_mode', None)
 
         for sub_name, sub_y in zip(self.func.sub_name(), self.func.sub(self.p_final, x_values, **self.fun_kwargs)):
             sub_y = check_complex(sub_y, actual_mode, self._data_complex)