diff --git a/tensorflow/python/keras/datasets/imdb.py b/tensorflow/python/keras/datasets/imdb.py
index 37403228edf..e359d691a5d 100644
--- a/tensorflow/python/keras/datasets/imdb.py
+++ b/tensorflow/python/keras/datasets/imdb.py
@@ -124,20 +124,24 @@ def load_data(path='imdb.npz',
   x_test = x_test[indices]
   labels_test = labels_test[indices]
 
-  xs = np.concatenate([x_train, x_test])
-  labels = np.concatenate([labels_train, labels_test])
-
   if start_char is not None:
-    xs = [[start_char] + [w + index_from for w in x] for x in xs]
+    x_train = [[start_char] + [w + index_from for w in x] for x in x_train]
+    x_test = [[start_char] + [w + index_from for w in x] for x in x_test]
   elif index_from:
-    xs = [[w + index_from for w in x] for x in xs]
+    x_train = [[w + index_from for w in x] for x in x_train]
+    x_test = [[w + index_from for w in x] for x in x_test]
 
   if maxlen:
-    xs, labels = _remove_long_seq(maxlen, xs, labels)
-    if not xs:
+    x_train, labels_train = _remove_long_seq(maxlen, x_train, labels_train)
+    x_test, labels_test = _remove_long_seq(maxlen, x_test, labels_test)
+    if not x_train or not x_test:
       raise ValueError('After filtering for sequences shorter than maxlen=' +
                        str(maxlen) + ', no sequence was kept. '
                        'Increase maxlen.')
+
+  xs = np.concatenate([x_train, x_test])
+  labels = np.concatenate([labels_train, labels_test])
+
   if not num_words:
     num_words = max(max(x) for x in xs)