diff --git a/ch12/autoencoder.py b/ch12/autoencoder.py
index d3f19c463..579516951 100644
--- a/ch12/autoencoder.py
+++ b/ch12/autoencoder.py
@@ -111,8 +111,7 @@ def call(self, inputs, training=None):
         x_hat = tf.reshape(x_hat, [-1, 28, 28])
 
         # [b, 28, 28] => [2b, 28, 28]
-        x_concat = tf.concat([x, x_hat], axis=0)
-        x_concat = x_hat
+        x_concat = tf.concat([x[:50], x_hat[:50]], axis=0)
         x_concat = x_concat.numpy() * 255.
         x_concat = x_concat.astype(np.uint8)
         save_images(x_concat, 'ae_images/rec_epoch_%d.png'%epoch)
diff --git a/ch12/vae.py b/ch12/vae.py
index 583ed33b8..fe65718a4 100644
--- a/ch12/vae.py
+++ b/ch12/vae.py
@@ -102,7 +102,7 @@ def call(self, inputs, training=None):
 model.build(input_shape=(4, 784))
 optimizer = tf.optimizers.Adam(lr)
 
-for epoch in range(1000):
+for epoch in range(100):
 
     for step, x in enumerate(train_db):