diff --git a/keras/backend/tensorflow_backend.py b/keras/backend/tensorflow_backend.py
index 2c1c06e4d..5b56e705d 100644
--- a/keras/backend/tensorflow_backend.py
+++ b/keras/backend/tensorflow_backend.py
@@ -1284,6 +1284,8 @@ def rnn(step_function, inputs, initial_states,
                 output, new_states = step_function(current_input,
                                                    tuple(states) +
                                                    tuple(constants))
+                for state, new_state in zip(states, new_states):
+                    new_state.set_shape(state.get_shape())
                 tiled_mask_t = tf.tile(mask_t, tf.pack([1, tf.shape(output)[1]]))
                 output = tf.select(tiled_mask_t, output, states[0])
                 new_states = [tf.select(tiled_mask_t, new_states[i], states[i]) for i in range(len(states))]
@@ -1295,6 +1297,8 @@ def rnn(step_function, inputs, initial_states,
                 output, new_states = step_function(current_input,
                                                    tuple(states) +
                                                    tuple(constants))
+                for state, new_state in zip(states, new_states):
+                    new_state.set_shape(state.get_shape())
                 output_ta_t = output_ta_t.write(time, output)
                 return (time + 1, output_ta_t) + tuple(new_states)