diff --git a/jmetal/algorithm/test/ittest_algorithm.py b/jmetal/algorithm/test/ittest_algorithm.py
index f214b774..beecb753 100644
--- a/jmetal/algorithm/test/ittest_algorithm.py
+++ b/jmetal/algorithm/test/ittest_algorithm.py
@@ -16,7 +16,7 @@ def setUp(self):
         self.offspring_size = 100
         self.mating_pool_size = 100
         self.max_evaluations = 100
-        self.mutation = PolynomialMutation(probability=1.0 / self.problem.number_of_variables, distribution_index=20)
+        self.mutation = PolynomialMutation(probability=1.0 / self.problem.number_of_variables(), distribution_index=20)
         self.crossover = SBXCrossover(probability=1.0, distribution_index=20)
 
     def test_NSGAII(self):
@@ -49,7 +49,7 @@ def test_should_NSGAII_work_when_solving_problem_ZDT1_with_standard_settings(sel
             problem=problem,
             population_size=100,
             offspring_population_size=100,
-            mutation=PolynomialMutation(probability=1.0 / problem.number_of_variables, distribution_index=20),
+            mutation=PolynomialMutation(probability=1.0 / problem.number_of_variables(), distribution_index=20),
             crossover=SBXCrossover(probability=1.0, distribution_index=20),
             termination_criterion=StoppingByEvaluations(max_evaluations=max_evaluations),
         )
@@ -68,7 +68,7 @@ def test_should_SMPSO_work_when_solving_problem_ZDT1_with_standard_settings(self
         algorithm = SMPSO(
             problem=problem,
             swarm_size=100,
-            mutation=PolynomialMutation(probability=1.0 / problem.number_of_variables, distribution_index=20),
+            mutation=PolynomialMutation(probability=1.0 / problem.number_of_variables(), distribution_index=20),
             leaders=CrowdingDistanceArchive(100),
             termination_criterion=StoppingByEvaluations(max_evaluations=25000),
         )