diff --git a/tests/test_cadet_reactions.py b/tests/test_cadet_reactions.py
index 241016b10..8ae00175b 100644
--- a/tests/test_cadet_reactions.py
+++ b/tests/test_cadet_reactions.py
@@ -16,7 +16,7 @@
 from CADETProcess.simulator import Cadet
 
 
-from test_cadet_adapter import found_cadet
+from tests.test_cadet_adapter import found_cadet
 
 
 def setup_process(unit_type):
diff --git a/tests/test_optimization_problem.py b/tests/test_optimization_problem.py
index 31e12ec8a..04e36ba06 100644
--- a/tests/test_optimization_problem.py
+++ b/tests/test_optimization_problem.py
@@ -11,7 +11,7 @@
     Structure, Float, List, SizedList, SizedNdArray, Polynomial, NdPolynomial
 )
 from CADETProcess.optimization import OptimizationProblem
-from optimization_problem_fixtures import (
+from tests.optimization_problem_fixtures import (
     LinearConstraintsSooTestProblem2,
     LinearEqualityConstraintsSooTestProblem
 )
@@ -330,7 +330,7 @@ def test_transform(self):
             )
 
 
-from test_events import TestHandler
+from tests.test_events import TestHandler
 class Test_OptimizationVariableEvents(unittest.TestCase):
 
     def __init__(self, methodName='runTest'):
diff --git a/tests/test_optimization_results.py b/tests/test_optimization_results.py
index 9f27a19fc..48ba94183 100644
--- a/tests/test_optimization_results.py
+++ b/tests/test_optimization_results.py
@@ -5,8 +5,8 @@
 from CADETProcess.optimization import OptimizationResults
 from CADETProcess.optimization import U_NSGA3
 
-from test_population import setup_population
-from test_optimization_problem import setup_optimization_problem
+from tests.test_population import setup_population
+from tests.test_optimization_problem import setup_optimization_problem
 
 
 def setup_optimization_results(
diff --git a/tests/test_parallelization_adapter.py b/tests/test_parallelization_adapter.py
index 9d441451a..ba8c91b6a 100644
--- a/tests/test_parallelization_adapter.py
+++ b/tests/test_parallelization_adapter.py
@@ -10,8 +10,8 @@
 from CADETProcess.simulator import Cadet
 from CADETProcess.optimization import SequentialBackend
 
-from test_cadet_adapter import detect_cadet
-from test_optimization_problem import setup_optimization_problem
+from tests.test_cadet_adapter import detect_cadet
+from tests.test_optimization_problem import setup_optimization_problem
 
 
 parallel_backends_module = importlib.import_module(
diff --git a/tests/test_population.py b/tests/test_population.py
index 3e0afc577..0b44eb328 100644
--- a/tests/test_population.py
+++ b/tests/test_population.py
@@ -4,7 +4,7 @@
 
 from CADETProcess import CADETProcessError
 from CADETProcess.optimization import Individual, Population, ParetoFront
-from test_individual import setup_individual
+from tests.test_individual import setup_individual
 enable_plot = False
 
 
diff --git a/tests/test_pymoo.py b/tests/test_pymoo.py
index be0a5210b..a27a08cff 100644
--- a/tests/test_pymoo.py
+++ b/tests/test_pymoo.py
@@ -2,7 +2,7 @@
 
 from CADETProcess.optimization import U_NSGA3
 
-from test_optimization_problem import setup_optimization_problem
+from tests.test_optimization_problem import setup_optimization_problem
 
 
 class Test_OptimizationProblemSimple(unittest.TestCase):