diff --git a/tensorflow/python/keras/layers/core.py b/tensorflow/python/keras/layers/core.py
index eb45636e677..b21801786d9 100644
--- a/tensorflow/python/keras/layers/core.py
+++ b/tensorflow/python/keras/layers/core.py
@@ -582,11 +582,11 @@ class Flatten(Layer):
 
     input_shape = tensor_shape.TensorShape(inputs.shape).as_list()
     if input_shape and all(input_shape[1:]):
-      outputs = array_ops.reshape(inputs, (-1, np.prod(input_shape[1:])))
+      outputs = array_ops.reshape(inputs, (-1, int(np.prod(input_shape[1:]))))
     else:
       outputs = array_ops.reshape(
           inputs, (tensor_shape.dimension_value(inputs.shape[0]) or
-                  array_ops.shape(inputs)[0], -1))
+                   array_ops.shape(inputs)[0], -1))
     if not context.executing_eagerly():
       outputs.set_shape(self.compute_output_shape(inputs.shape))
     return outputs