diff --git a/art/experimental/attacks/evasion/fast_gradient.py b/art/experimental/attacks/evasion/fast_gradient.py
index 48a6b2d9ac..5278cadf5a 100644
--- a/art/experimental/attacks/evasion/fast_gradient.py
+++ b/art/experimental/attacks/evasion/fast_gradient.py
@@ -358,12 +358,4 @@ def _compute(
             x_adv_result.append(x_adv_batch['pixel_values'])
 
         x_adv_result = torch.concatenate(x_adv_result)
-        sentinel = object()
-
-        def myfunc(adv, x_sample=sentinel):
-            if x_sample is sentinel:
-                x_sample = x_adv
-            x_sample['pixel_values'] = adv.type(original_type)
-            return x_sample
-
-        return myfunc(x_adv_result, x_sample=x_adv)
+        return x_adv.update_pixels(x_adv_result)
diff --git a/art/experimental/estimators/hugging_face_multimodal/hugging_face_mm_inputs.py b/art/experimental/estimators/hugging_face_multimodal/hugging_face_mm_inputs.py
index d10ab8510d..e3f9c763b4 100644
--- a/art/experimental/estimators/hugging_face_multimodal/hugging_face_mm_inputs.py
+++ b/art/experimental/estimators/hugging_face_multimodal/hugging_face_mm_inputs.py
@@ -184,6 +184,9 @@ def __len__(self) -> int:
         pixel_values = UserDict.__getitem__(self, "pixel_values")
         return len(pixel_values)
 
+    def update_pixels(self, pixel_values: torch.Tensor) -> None:
+        super().__setitem__("pixel_values", pixel_values)
+
     def reshape(self, new_shape: Tuple) -> HuggingFaceMultiModalInput:
         """
         Defines reshaping on the HuggingFaceMultiModalInput input.