diff --git a/src/festim/hydrogen_transport_problem.py b/src/festim/hydrogen_transport_problem.py
index d7e7f9bd6..bc2e44249 100644
--- a/src/festim/hydrogen_transport_problem.py
+++ b/src/festim/hydrogen_transport_problem.py
@@ -1380,14 +1380,17 @@ def mixed_term(u, v, n):
         self.J = dolfinx.fem.form(J, entity_maps=entity_maps)
 
     def create_solver(self):
-        self.solver = NewtonSolver(
+        self.solver = NewNewtonSolver(
             self.forms,
-            self.J,
             [subdomain.u for subdomain in self.volume_subdomains],
             bcs=self.bc_forms,
-            max_iterations=self.settings.max_iterations,
+            J=self.J,
+            # max_iterations=self.settings.max_iterations,
             petsc_options=self.petsc_options,
         )
+        self.solver.atol = self.settings.atol
+        self.solver.rtol = self.settings.rtol
+        self.solver.max_it = self.settings.max_iterations
 
     def create_flux_values_fenics(self):
         """For each particle flux create the ``value_fenics`` attribute"""
@@ -1447,7 +1450,7 @@ def iterate(self):
         self.update_time_dependent_values()
 
         # solve main problem
-        self.solver.solve(self.settings.atol, self.settings.rtol)
+        self.solver.solve()
 
         # post processing
         self.post_processing()
@@ -1475,7 +1478,7 @@ def run(self):
                 self.progress_bar.refresh()  # refresh progress bar to show 100%
         else:
             # Solve steady-state
-            self.solver.solve(self.settings.rtol)
+            self.solver.solve()
             self.post_processing()
 
     def __del__(self):
diff --git a/test/system_tests/test_multi_material.py b/test/system_tests/test_multi_material.py
index 7d2720d09..07ac562a8 100644
--- a/test/system_tests/test_multi_material.py
+++ b/test/system_tests/test_multi_material.py
@@ -142,7 +142,7 @@ def c_exact_bot_np(x):
 
     my_model.temperature = 500.0  # lambda x: 300 + 10 * x[1] + 100 * x[0]
 
-    my_model.settings = F.Settings(atol=None, rtol=1e-5, transient=False)
+    my_model.settings = F.Settings(atol=1e-5, rtol=1e-5, transient=False)
     my_model.exports = [
         F.VTXSpeciesExport(f"u_{subdomain.id}.bp", field=H, subdomain=subdomain)
         for subdomain in my_model.volume_subdomains
@@ -216,7 +216,7 @@ def test_1_material_discontinuous_version():
 
     my_model.temperature = lambda x: 300 + 100 * x[0]
 
-    my_model.settings = F.Settings(atol=None, rtol=1e-5, transient=False)
+    my_model.settings = F.Settings(atol=1e-5, rtol=1e-5, transient=False)
 
     my_model.exports = [
         F.VTXSpeciesExport(
@@ -384,7 +384,7 @@ def test_2_mats_particle_flux_bc():
 
     my_model.temperature = lambda x: 300 + 10 * x[1] + 100 * x[0]
 
-    my_model.settings = F.Settings(atol=None, rtol=1e-5, transient=False)
+    my_model.settings = F.Settings(atol=1e-5, rtol=1e-5, transient=False)
 
     my_model.exports = [
         F.VTXSpeciesExport(f"u_{subdomain.id}.bp", field=H, subdomain=subdomain)