diff --git a/src/f3dasm/_src/optimization/adapters/scipy_implementations.py b/src/f3dasm/_src/optimization/adapters/scipy_implementations.py
index 832b9258..1c412df5 100644
--- a/src/f3dasm/_src/optimization/adapters/scipy_implementations.py
+++ b/src/f3dasm/_src/optimization/adapters/scipy_implementations.py
@@ -65,6 +65,9 @@ def fun(x):
 
         self.options['maxiter'] = iterations
 
+        if not hasattr(data_generator, 'dfdx'):
+            data_generator.dfdx = None
+
         minimize(
             fun=fun,
             method=self.method,