diff --git a/docs/tutorials/gluon/mnist.md b/docs/tutorials/gluon/mnist.md
index 3758f561a573..5a4a37551eae 100644
--- a/docs/tutorials/gluon/mnist.md
+++ b/docs/tutorials/gluon/mnist.md
@@ -279,6 +279,7 @@ trainer = gluon.Trainer(net.collect_params(), 'sgd', {'learning_rate': 0.03})
 
 ```python
 # Use Accuracy as the evaluation metric.
+epoch = 10
 metric = mx.metric.Accuracy()
 softmax_cross_entropy_loss = gluon.loss.SoftmaxCrossEntropyLoss()