diff --git a/tests/test_clustering.py b/tests/test_clustering.py
index 00fec9e..7e08782 100644
--- a/tests/test_clustering.py
+++ b/tests/test_clustering.py
@@ -121,7 +121,7 @@ def test_force_clustering():
         [0.1, 0.2, 0.4, 0.6, 1]
     ])
     dataset.classes = {0: 0}
-    dataset.cluster_stratification = {"cluster1": np.array([0]), "cluster2": np.array([0]), "cluster3": np.array([0]), "cluster4": np.array([0]), "5": np.array([0])}
+    dataset.cluster_stratification = {"cluster1": np.array([0]), "cluster2": np.array([0]), "cluster3": np.array([0]), "cluster4": np.array([0]), "cluster5": np.array([0])}
     dataset.num_clusters = 3
 
     # Call the force_clustering function