diff --git a/examples/transformer.py b/examples/transformer.py
index 375f4ca907..40082db71c 100755
--- a/examples/transformer.py
+++ b/examples/transformer.py
@@ -17,7 +17,7 @@ def make_dataset():
   random.shuffle(ds)
   ds = np.array(ds).astype(np.float32)
   ds_X = ds[:, 0:6]
-  ds_Y = np.copy(ds[:, 1:])
+  ds_Y = np.copy(ds[:, 1:]).astype(np.int32)
   ds_X_train, ds_X_test = ds_X[0:8000], ds_X[8000:]
   ds_Y_train, ds_Y_test = ds_Y[0:8000], ds_Y[8000:]
   return ds_X_train, ds_Y_train, ds_X_test, ds_Y_test