diff --git a/pysegcnn/core/trainer.py b/pysegcnn/core/trainer.py
index 50b91d62dfbb2d5135566a4bb56b4d00f7bd9d01..4d41611295be2b50ee81deca0ff9f9381cb981a8 100644
--- a/pysegcnn/core/trainer.py
+++ b/pysegcnn/core/trainer.py
@@ -2706,8 +2706,10 @@ class NetworkInference(BaseConfig):
                 str(base_name.name).replace(fold_number, 'kfold'))
 
             # predictions of the different models
-            y_true = [output['y_true'] for output in inference.values()]
-            y_pred = [output['y_pred'] for output in inference.values()]
+            y_true = np.asarray(
+                [output['y_true'] for output in inference.values()]).flatten()
+            y_pred = np.asarray(
+                [output['y_pred'] for output in inference.values()]).flatten()
 
             # calculate classification over all different models
             LOGGER.info('Aggregating statistics of models:')