diff --git a/gempy/library/matching.py b/gempy/library/matching.py
index e9147c292..9ba6fca4f 100644
--- a/gempy/library/matching.py
+++ b/gempy/library/matching.py
@@ -396,7 +396,7 @@ def bounds_for_unfixed_parameters(m):
         if self._method is not None:
             kwargs['method'] = self._method
 
-        if 'minimizer_kwargs' in arg_names:
+        if 'minimizer_kwargs' in kwarg_names:
             kwargs['minimizer_kwargs'] = {'args': farg,
                                           'method': 'Nelder-Mead'}