diff --git a/keras_export/convert_model.py b/keras_export/convert_model.py
index 91bf7073..66fa9259 100755
--- a/keras_export/convert_model.py
+++ b/keras_export/convert_model.py
@@ -566,6 +566,7 @@ def show_multi_head_attention_layer(layer):
     assert len(layer.input_shape) == 3
     assert layer.input_shape[0] is None
     assert layer._output_shape is None
+    assert layer._attention_axes == (1,), "MultiHeadAttention supported only with attention_axes=None"
     return {
         'weight_shapes': list(map(lambda w: list(w.shape), layer.weights)),
         'weights': list(map(lambda w: encode_floats(w.numpy()), layer.weights)),