@@ -251,7 +251,7 @@ def test_generate_images(self):
 actual_parameters = predict_kwargs["parameters"]
 actual_instance = predict_kwargs["instances"][0]
 assert actual_instance["prompt"] == prompt1
-assert actual_instance["negativePrompt"] == negative_prompt1
+assert actual_parameters["negativePrompt"] == negative_prompt1
 # TODO(b/295946075) The service stopped supporting image sizes.
 # assert actual_parameters["sampleImageSize"] == str(max(width, height))
 # assert actual_parameters["aspectRatio"] == f"{width}:{height}"

@@ -174,10 +174,6 @@ def _generate_images(
 "number_of_images_in_batch": number_of_images,
 }
 
-if negative_prompt:
-instance["negativePrompt"] = negative_prompt
-shared_generation_parameters["negative_prompt"] = negative_prompt
-
 if base_image:
 base_image_base64 = (
 base_image._as_base64_string()
@@ -207,6 +203,9 @@ def _generate_images(
 parameters["aspectRatio"] = f"{width}:{height}"
 
 parameters["sampleCount"] = number_of_images
+if negative_prompt:
+parameters["negativePrompt"] = negative_prompt
+shared_generation_parameters["negative_prompt"] = negative_prompt
 
 if seed is not None:
 # Note: String seed and numerical seed give different results