diff --git a/keras_contrib/optimizers/ftml.py b/keras_contrib/optimizers/ftml.py
index 6a5eb37..edfb9d7 100644
--- a/keras_contrib/optimizers/ftml.py
+++ b/keras_contrib/optimizers/ftml.py
@@ -2,6 +2,7 @@ from __future__ import absolute_import
 from keras.optimizers import Optimizer
 from .. import backend as K
 from keras.utils.generic_utils import get_custom_objects
+from keras.legacy import interfaces
 
 
 class FTML(Optimizer):