diff --git a/src/py/flwr/server/strategy/bulyan_test.py b/src/py/flwr/server/strategy/bulyan_test.py
index 1979c690a31c..9cab61406f0b 100644
--- a/src/py/flwr/server/strategy/bulyan_test.py
+++ b/src/py/flwr/server/strategy/bulyan_test.py
@@ -129,4 +129,5 @@ def test_aggregate_fit() -> None:
         actual_list = parameters_to_ndarrays(actual_aggregated)
         actual = actual_list[0]
         assert (actual == expected[0]).all()
-    raise ValueError("aggregate_fit function returned None")
+    else:
+        raise ValueError("aggregate_fit function returned None")
diff --git a/src/py/flwr/server/strategy/fedadagrad_test.py b/src/py/flwr/server/strategy/fedadagrad_test.py
index 036b98d5af15..a28776c20e90 100644
--- a/src/py/flwr/server/strategy/fedadagrad_test.py
+++ b/src/py/flwr/server/strategy/fedadagrad_test.py
@@ -84,4 +84,5 @@ def test_aggregate_fit() -> None:
         actual_list = parameters_to_ndarrays(actual_aggregated)
         actual = actual_list[0]
         assert (actual == expected[0]).all()
-    raise ValueError("aggregate_fit function returned None")
+    else:
+        raise ValueError("aggregate_fit function returned None")
diff --git a/src/py/flwr/server/strategy/fedmedian_test.py b/src/py/flwr/server/strategy/fedmedian_test.py
index 03f6a37025a8..18d2159d9f8b 100644
--- a/src/py/flwr/server/strategy/fedmedian_test.py
+++ b/src/py/flwr/server/strategy/fedmedian_test.py
@@ -198,4 +198,5 @@ def test_aggregate_fit() -> None:
         actual_list = parameters_to_ndarrays(actual_aggregated)
         actual = actual_list[0]
         assert (actual == expected[0]).all()
-    raise ValueError("aggregate_fit function returned None")
+    else:
+        raise ValueError("aggregate_fit function returned None")
diff --git a/src/py/flwr/server/strategy/krum_test.py b/src/py/flwr/server/strategy/krum_test.py
index 3f7985432084..1ffb92c649d2 100644
--- a/src/py/flwr/server/strategy/krum_test.py
+++ b/src/py/flwr/server/strategy/krum_test.py
@@ -199,4 +199,5 @@ def test_aggregate_fit() -> None:
         actual_list = parameters_to_ndarrays(actual_aggregated)
         actual = actual_list[0]
         assert (actual == expected[0]).all()
-    raise ValueError("aggregate_fit function returned None")
+    else:
+        raise ValueError("aggregate_fit function returned None")
diff --git a/src/py/flwr/server/strategy/multikrum_test.py b/src/py/flwr/server/strategy/multikrum_test.py
index 43763016cd6b..ee9694da841c 100644
--- a/src/py/flwr/server/strategy/multikrum_test.py
+++ b/src/py/flwr/server/strategy/multikrum_test.py
@@ -98,4 +98,5 @@ def test_aggregate_fit() -> None:
         actual_list = parameters_to_ndarrays(actual_aggregated)
         actual = actual_list[0]
         assert (actual == expected[0]).all()
-    raise ValueError("aggregate_fit function returned None")
+    else:
+        raise ValueError("aggregate_fit function returned None")