diff --git a/tensorflow/python/keras/backend.py b/tensorflow/python/keras/backend.py
index ce557b834d5..c7ebb4b2524 100644
--- a/tensorflow/python/keras/backend.py
+++ b/tensorflow/python/keras/backend.py
@@ -5429,9 +5429,9 @@ def ctc_label_dense_to_sparse(labels, label_lengths):
   num_batches_tns = array_ops.stack([label_shape[0]])
   max_num_labels_tns = array_ops.stack([label_shape[1]])
 
-  def range_less_than(_, current_input):
+  def range_less_than(old_input, current_input):
     return array_ops.expand_dims(
-        math_ops.range(label_shape[1]), 0) < array_ops.fill(
+        math_ops.range(array_ops.shape(old_input)[1]), 0) < array_ops.fill(
             max_num_labels_tns, current_input)
 
   init = math_ops.cast(
diff --git a/tensorflow/python/keras/backend_test.py b/tensorflow/python/keras/backend_test.py
index e3bc5467261..51b57d2d1ff 100644
--- a/tensorflow/python/keras/backend_test.py
+++ b/tensorflow/python/keras/backend_test.py
@@ -1661,6 +1661,7 @@ class BackendCrossEntropyLossesTest(test.TestCase):
 
 
 @test_util.run_all_in_graph_and_eager_modes
+@test_util.with_control_flow_v2
 class TestCTC(test.TestCase):
 
   def test_ctc_decode(self):