diff --git a/resnet.py b/resnet.py
index 1e4585f..bd90b32 100755
--- a/resnet.py
+++ b/resnet.py
@@ -52,7 +52,7 @@ use_image_generator = True
 def prepare(X, y):
     X = X.reshape(X.shape[0], 1, width, height).astype('float32') / 255
     # convert class vectors to binary class matrices
-    Y = to_categorical(y_train, nb_classes)
+    Y = to_categorical(y, nb_classes)
     return X, Y
 
 # the data, shuffled and split between train and test sets