diff --git a/library/chroma_models.py b/library/chroma_models.py
index b9c54db4..0c93f526 100644
--- a/library/chroma_models.py
+++ b/library/chroma_models.py
@@ -695,6 +695,7 @@ class Chroma(Flux):
                 input_vec = self.get_input_vec(timesteps, guidance, img.shape[0])
 
                 # kohya-ss: I'm not sure why requires_grad is set to True here
+                # original code: https://github.com/lodestone-rock/flow/blob/c76f63058980d0488826936025889e256a2e0458/src/models/chroma/model.py#L217
                 input_vec.requires_grad = True
                 mod_vectors = self.distilled_guidance_layer(input_vec)
         else: